Enable VTOrc in backup tests

[GuptaManan100]

Description

This PR enables VTOrc for the backup tests that take backup of a replica. Unfortunately, we can't enable VTOrc for the tests that take backup from primary tablets, since VTOrc will see there is no primary and end up promoting one which interferes with the tests invariants.

Related Issue(s)

• RFC: Orchestrator as a native Vitess component #6612

Checklist

• "Backport me!" label has been added if this change should be backported
• Tests were added or are not required
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

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[rsajwani]

LGTM

[GuptaManan100]

The reduction in the topo-refresh-time for VTOrc is a nice optimization in making the tests faster.

Before -

After -

This just helps VTOrc setup faster, so it shaves off about 10 seconds from all the tests. Earlier with the default, it took VTOrc 15 seconds to even read the tablets' information from the topology server. With the flag change, it discovers the tablets in 3 or 6 seconds. Once it has read the tablets for the first time, it doesn't matter much when we refresh the information because none of the tests actually change the tablet record. The operations that do, automatically trigger a refresh irrespective of the timer. So overall it has a lower impact for long-running tests, but is much more useful for shorter tests.

[GuptaManan100]

This timeout has been increased for VTOrc. With the defaults, it takes VTOrc 15 seconds to discover the tablets and then it can start repairing them. This wait was for 10 seconds which turned out to be too small. I have improved VTOrc performance ☝️, but it doesn't hurt to increase the timeout.