Coverity found a Quality issue: Data race condition

Details:

Coverity Issue ID: 185621
Issue Description: Thread shared data is accessed without holding an appropriate lock, possibly causing a race condition
Potential Impact: The value of the shared data will be determined by the interleaving of thread execution.
Coverity checker: MISSING_LOCK
Branch: v8.0
File path: /src/mongo/db/s/migration_chunk_cloner_source.cpp
Line number: Unknown

What Coverity Detected

Example 1 (cont.): "mongo::MigrationChunkClonerSource._jumboChunkCloneState" is written to in call to "emplace" with lock "mongo::MigrationChunkClonerSource._mutex" held.

The issue can be viewed in Coverity here.

How do I fix this?

Refer to https://wiki.corp.mongodb.com/spaces/HGTC/pages/385852267/Guidance+on+fixing+Coverity+issues for guidance on fixing Coverity issues.

Note: This issue was found on the v8.0 branch. If a fix is needed, you must create a BACKPORT ticket following the Server BACKPORT policy