In the context of version vector/unicast, make log servers return an empty version range (on peeks) only when it is correct to do so. This is so the receiver will receive all versions (even though the sender is sending an empty version range) that it is supposed to receive.

Changes:

Make the cluster controller collect the set of log servers participated in recovery and propagate that information to the other processes.
Extend the ServerPeekCursor to take a flag that tells the source log server whether it can return an empty version range or not (in the context of version vector/unicast), and make the source log server return an empty version range only when this flag is set.
Make the peek APIs set the flag appropriately when initializing ServerPeekCursors.
Also, take the internal logic used by SetPeekCursor and MergedPeekCursor into account while initializing the above mentioned flag.

Testing:

Joshua id (with version vector disabled): 20250609-200159-sre-0c15ba89fee21207 (no failures).

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Jun 09 '25 19:06 sbodagala

Result of foundationdb-pr-clang-ide on Linux RHEL 9

Commit ID: 4ec7e4de298be9b6936b7ac58f963a3a4808c3f8
Duration 0:25:38
Result: :white_check_mark: SUCCEEDED
Error: N/A
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Jun 09 '25 20:06 foundationdb-ci

Result of foundationdb-pr-macos-m1 on macOS Ventura 13.x

Commit ID: 4ec7e4de298be9b6936b7ac58f963a3a4808c3f8
Duration 0:38:58
Result: :white_check_mark: SUCCEEDED
Error: N/A
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Jun 09 '25 20:06 foundationdb-ci

Result of foundationdb-pr-clang-arm on Linux CentOS 7

Commit ID: 4ec7e4de298be9b6936b7ac58f963a3a4808c3f8
Duration 0:49:23
Result: :white_check_mark: SUCCEEDED
Error: N/A
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Jun 09 '25 20:06 foundationdb-ci

Result of foundationdb-pr-clang on Linux RHEL 9

Commit ID: 4ec7e4de298be9b6936b7ac58f963a3a4808c3f8
Duration 0:51:22
Result: :white_check_mark: SUCCEEDED
Error: N/A
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Build Workspace zip file of the working directory (available for 30 days)

Jun 09 '25 20:06 foundationdb-ci

Result of foundationdb-pr on Linux RHEL 9

Commit ID: 4ec7e4de298be9b6936b7ac58f963a3a4808c3f8
Duration 0:59:47
Result: :white_check_mark: SUCCEEDED
Error: N/A
Build Log terminal output (available for 30 days)
Build Workspace zip file of the working directory (available for 30 days)

Jun 09 '25 20:06 foundationdb-ci

Result of foundationdb-pr-cluster-tests on Linux RHEL 9

Commit ID: 4ec7e4de298be9b6936b7ac58f963a3a4808c3f8
Duration 1:01:39
Result: :white_check_mark: SUCCEEDED
Error: N/A
Build Log terminal output (available for 30 days)
Build Workspace zip file of the working directory (available for 30 days)
Cluster Test Logs zip file of the test logs (available for 30 days)

Jun 09 '25 20:06 foundationdb-ci