[mergify]: keep the house clean for conflicts in automated bumps

[v1v]

What does this PR do?

Close obsoleted PRs that are related to the automated bumps when they are in conflict.

For instance: #29385

Therefore, it's not needed to be resolved but wait for the more up-to-date PRs to be merged.

[elasticmachine]

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• Start Time: 2021-12-15T16:54:20.573+0000

• Duration: 16 min 57 sec

• Commit: 50a264c

Test stats 🧪

Test	Results
Failed	0
Passed	3
Skipped	0
Total	3

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