Bump ecj from 3.30.0 to 3.31.0 in /common
Bump ecj from 3.30.0 to 3.31.0 in /common

Bumps [ecj](https://github.com/eclipse-jdt/eclipse.jdt.core) from 3.30.0 to 3.31.0.
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Fixes #1363

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/auto/pull/1363 from google:dependabot/maven/common/org.eclipse.jdt-ecj-3.31.0 6bdb8a0b0752fe46d18feca8634e0d62d90e11f9
PiperOrigin-RevId: 474283930

google/auto,eamonnmcmanus/auto,eamonnmcmanus/auto,google/auto,google/auto,eamonnmcmanus/auto