settings: remove browser.startup.homepage_override.buildID test
settings: remove browser.startup.homepage_override.buildID test

Remove the browser.startup.homepage_override.buildID test for Tor Browser
6.5 and nightly. After #19528 the buildID is now changing with each
release.

boklm/tbb-testsuite,boklm/tbb-testsuite,boklm/tbb-testsuite,boklm/tbb-testsuite,boklm/tbb-testsuite