RFR: CODETOOLS-7903235: JOL: Improve GHA triggers

[Aleksey Shipilev]

GHA workflows need to have a push-based trigger instead of pull_request one, in order to comply with current scheme of running actions in private forks.

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jol/pull/30/files
 Webrev: https://webrevs.openjdk.org/?repo=jol&pr=30&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903235
  Stats: 4 lines in 1 file changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jol/pull/30.diff
  Fetch: git fetch https://git.openjdk.org/jol pull/30/head:pull/30

PR: https://git.openjdk.org/jol/pull/30