test(e2e): silence timing-dependent Vite logs in vitest browser fixture

[wan9chi]

Motivation

vitest_browser_cache fails every so often on macOS x64 CI because an extra line shows up in the snapshot:

+2:09:21 AM [vite] (client) [optimizer] scanning dependencies...

Recent failures: 36318877151 (attempt 1), 36087090263, 36084775576, 36084774143, 31664423600.

Vite's dependency optimizer prints [optimizer] scanning dependencies... if the scan takes longer than 1s, and [optimizer] bundling dependencies... if bundling does. Both depend on how fast the runner is.

Change

Run the fixture's task as VITEST_BROWSER_DEBUG=false vitest run.

Vitest browser mode hard-codes the browser server's Vite log level to process.env.VITEST_BROWSER_DEBUG ?? "info", so logLevel in the config has no effect. "false" is the only value that silences that logger without also turning on the browser-side debug output. Any other non-empty value, warn included, turns on client debug RPC logs that contain session IDs, ports and timings.

I forced both timers to fire with artificially slow plugins. Without the variable, both messages were printed; with it, neither was. The test result line and the JSON report output were unaffected.

[github-actions]

fspy benchmark

linux

dynamic/launch             change  +1.74%  [-13.56% .. +20.36%]  overhead  +285.25%
dynamic/access             change  +1.35%  [ -3.71% ..  +7.20%]  overhead   +20.05%
dynamic/access-relative    change  +0.00%  [ -3.31% ..  +4.14%]  overhead   +66.26%
dynamic/access-contended   change  -0.73%  [ -7.41% ..  +5.21%]  overhead   +35.78%
static/launch              change  +1.03%  [ -8.73% .. +13.86%]  overhead  +698.25%
static/access              change  +0.17%  [ -0.71% ..  +1.22%]  overhead +1459.98%
static/access-relative     change  -0.35%  [ -1.54% ..  +0.56%]  overhead +1941.13%
static/access-contended    change  -0.17%  [ -1.29% ..  +0.50%]  overhead +1686.01%

macos

dynamic/launch             change  -0.37%  [ -5.19% ..  +5.00%]  overhead  +219.94%
dynamic/access             change  -2.24%  [-15.27% ..  +9.24%]  overhead    +2.00%
dynamic/access-relative    change  +1.27%  [ -3.57% ..  +6.15%]  overhead  +264.80%
dynamic/access-contended   change  -0.53%  [ -9.96% ..  +3.81%]  overhead    +1.72%

windows

dynamic/launch             change  -0.06%  [ -5.22% ..  +7.84%]  overhead   +23.05%
dynamic/access             change  -0.35%  [ -2.43% ..  +2.34%]  overhead    +1.96%
dynamic/access-relative    change  +0.00%  [ -1.36% ..  +1.06%]  overhead    +1.63%
dynamic/access-contended   change  -0.17%  [ -1.53% ..  +1.39%]  overhead    +1.61%