Code coverage cannot be disabled in stock runner

[CharlieHess]

Bug description

In the action source, action.yml exposes coverageOptions, but the Linux runner script dist/platforms/ubuntu/run_tests.sh always appends all three flags:

-coverageResultsPath "$FULL_COVERAGE_RESULTS_PATH"
-enableCodeCoverage
-coverageOptions "$COVERAGE_OPTIONS"

How to reproduce

The Linux implementation always passes -enableCodeCoverage, which can crash certain Unity versions before tests execute.
coverageOptions: '' is not a valid opt-out because coverage is still enabled.

Expected behavior

Request: add an explicit boolean to disable coverage entirely, or only append coverage flags when coverage was requested.

Additional details

On our repo and current Unity 6000.3.4f1, the stock action crashes before PlayMode tests start: #301. Its log shows the stock docker launch carrying coverage env, then Unity dies during PlayMode assembly reload with native signal 11 / exit 139, and the stack goes through ScriptingCoverage::FilterRecordedMethods. So there are major issues with code coverage.

[frostebite]

Opened #311 to add a coverageEnabled boolean input (default true, no behavior change unless you opt out) that omits -enableCodeCoverage/-coverageOptions/-coverageResultsPath entirely when set to false, on both the Linux and Windows scripts. This also looks like the likely root cause of #301 and #306 — flagged there too.