[BUG] Schedule reroute after allocator timeout

[imRishN]

Describe the bug

When the existing shards allocator would timeout in batch mode, we would need to attempt another reroute such that next iteration is in line. Currently, applyStartedShards, applyFailedShards, async fetch, etc would internally trigger a subsequent reroute from the previous batch. But this behaviour might not be guaranteed.

Related PR comment - #14848 (comment)

Related component

Other

To Reproduce

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2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior

Trigger subsequent reroute on timeout

Additional Details

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Host/Environment (please complete the following information):

• OS: [e.g. iOS]
• Version [e.g. 22]

Additional context
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[peternied]

[Triage - attendees 1 2]
@imRishN Thanks for creating this issue, could you make a pull request to address this or update the description to remove to make it clearer what should be done for another community member?