mb.py's analyze feature causes CLs that contain only OWNERS files to compile and run tests.

As an example, https://crrev.com/c/1121097 contains only OWNERS files but the analyze step on many of the bots "Found dependency" and even some bots that found "No dependency" still compiled, possibly due to analyze_matched_exclusion.

Specifically:
1. https://ci.chromium.org/p/chromium/builders/luci.chromium.try/android_arm64_dbg_recipe/70470:
  * Appears to have found many compile_targets and four test_targets.
  * analyze_matched_exclusion Analyze disabled: matched exclusion
2. https://ci.chromium.org/p/chromium/builders/luci.chromium.try/win_chromium_compile_dbg_ng/75880:
  * Appears to have found five test_targets.
  * analyze_matched_exclusion Analyze disabled: matched exclusion
3. https://ci.chromium.org/p/chromium/builders/luci.chromium.try/linux_vr/1252:
  * The analyze step found "No dependency", but, unlike issue 862731, it did not report "No compile necessary" in the steps overview. Maybe that is because of the next item, though it's strange that the next item does not run in that case.
  * analyze_matched_exclusion Analyze disabled: matched exclusion

All of the "analyze_matched_exclusion Analyze disabled: matched exclusion" were:
tools/perf/contrib/vr_benchmarks/OWNERS (regex = 'tools/perf/.*')

Does this mean that changing any file under tools/perf/ will force a compile? This doesn't appear to be the only problem, though, since the first two bots above found compile and/or test targets.