CSTACKEX-337: fixing the bug for First VM deployment double-counts template size (#125)

template size is counted twice when calculating the minimum primary
storagepool size required
 
<img width="2196" height="902" alt="image"
src="https://github.com/user-attachments/assets/009bc45f-4375-41f7-ae1c-90edca683a87"
/>


### Description

storagePoolHasEnoughSpace accepts a pool when allocatedSizeWithTemplate
+ totalAskingSize fits. On the first VM deploy from a template onto a
managed pool, the template size was added on both sides.

For a root volume, the method passes the template into
getAllocatedPoolCapacity, which stored it in allocatedSizeWithTemplate.
It then adds the volume size and
getAskingSizeForTemplateBasedOnClusterAndStoragePool into
totalAskingSize. That second call returns the template size again from
getBytesRequiredForTemplate when the pool is managed and clusterId is
set. The check asked for used bytes + volume size + 2 × template size.

Managed pools now return only getUsedBytes from
getAllocatedPoolCapacity. The template is reserved once, in
totalAskingSize. This extra add came from Dell's PowerFlex PR.Before
that, a managed pool contributed only getUsedBytes to
allocatedSizeWithTemplate.

This PR...
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### Types of changes

- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] New feature (non-breaking change which adds functionality)
- [X] Bug fix (non-breaking change which fixes an issue)
- [ ] Enhancement (improves an existing feature and functionality)
- [ ] Cleanup (Code refactoring and cleanup, that may add test cases)
- [ ] Build/CI
- [ ] Test (unit or integration test code)

### Feature/Enhancement Scale or Bug Severity

#### Feature/Enhancement Scale

- [ ] Major
- [X] Minor

#### Bug Severity

- [ ] BLOCKER
- [ ] Critical
- [ ] Major
- [X] Minor
- [ ] Trivial

### Screenshots (if appropriate):

### How Has This Been Tested?
ISCSI VM creation , allocated size get's only used bytes of pool for
first time VM creation
<img width="1403" height="272" alt="Screenshot 2026-10-15 at 6 52 45 PM"
src="https://github.com/user-attachments/assets/3d862c7b-a8fe-472c-9857-29003284cb22"
/>
NFS VM creation , allocated size get's only used bytes of pool for first
time VM creation
<img width="1402" height="358" alt="Screenshot 2026-10-15 at 8 37 29 PM"
src="https://github.com/user-attachments/assets/88bdca34-3144-45f2-a081-4f864a48ed39"
/>
<img width="1453" height="271" alt="Screenshot 2026-10-15 at 8 38 43 PM"
src="https://github.com/user-attachments/assets/7b3635c5-d1df-4cf2-b38b-71dce915410e"
/>
BOTH NFS AND ISCSI POOLS WERE MADE OF 18 GB and succeeded
<img width="1517" height="118" alt="Screenshot 2026-10-15 at 8 38 52 PM"
src="https://github.com/user-attachments/assets/ba7607d6-c176-4216-88ab-3b934c5df549"
/>

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Author: sathvikaragi

server/src/main/java/com/cloud/capacity/CapacityManagerImpl.java

@@ -573,25 +573,16 @@ public long getUsedIops(StoragePoolVO pool) {
         throw new CloudRuntimeException("Storage driver in CapacityManagerImpl.getUsedIops(StoragePoolVO) is not a PrimaryDataStoreDriver.");
     }
 
+    //Managed pool, return value contains used size of the pool.
+    //Unmanaged pool, return value contains used pool size and template size.
     @Override
     public long getAllocatedPoolCapacity(StoragePoolVO pool, VMTemplateVO templateForVmCreation) {
         long totalAllocatedSize;
 
         // if the storage pool is managed, the used bytes can be larger than the sum of the sizes of all of the non-destroyed volumes
         // in this case, call getUsedBytes(StoragePoolVO)
         if (pool.isManaged()) {
-            totalAllocatedSize = getUsedBytes(pool);
-
-            if (templateForVmCreation != null) {
-                VMTemplateStoragePoolVO templatePoolVO = _templatePoolDao.findByPoolTemplate(pool.getId(), templateForVmCreation.getId(), null);
-                if (templatePoolVO == null) {
-                    // template is not installed in the pool, consider the template size for allocation
-                    long templateForVmCreationSize = templateForVmCreation.getSize() != null ? templateForVmCreation.getSize() : 0;
-                    totalAllocatedSize += templateForVmCreationSize;
-                }
-            }
-
-            return totalAllocatedSize;
+            return getUsedBytes(pool);
         } else {
             // Get size for all the non-destroyed volumes.
             Pair<Long, Long> sizes = _volumeDao.getNonDestroyedCountAndTotalByPool(pool.getId());