v14 backport of two PRs: vreplication throttling info & vreplication endtoend flakiness fix

[shlomi-noach]

This PR backports to v14 both:

• https://github.com/vitessio/vitess/pull/10601
• https://github.com/vitessio/vitess/pull/10876

The intention was to just backport https://github.com/vitessio/vitess/pull/10876 to fix onlineddl_vrepl CI flakiness, but it then depends on #10601 so we're backporting that, too.

[vitess-bot[bot]]

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[shlomi-noach]

Ironically onlineddl_vrepl fails.

[deepthi]

#10601 is too big to back port to the release branch. we should back port as much of #10876 as we can, OR find an alternative way to fix the flakiness.

[shlomi-noach]

We;re good test-wise.

[deepthi]

We;re good test-wise.

Meaning we can close this without merging?

[shlomi-noach]

Meaning we can close this without merging?

Sorry, missed this comment. No - meaning the tests for this PR are green ad fixed. This PR should be merged.