Attempting to read a partition via `SELECT * FROM MUTATION_FRAGMENTS()`, which the node doesn't own, from a table using tablets causes a crash.
This is because when using tablets, the replica side simply doesn't handle requests for un-owned tokens and this triggers a crash.
We should probably improve how this is handled (an exception is better than a crash), but this is outside the scope of this PR.
This PR fixes this and also adds a reproducer test.
Fixes: https://github.com/scylladb/scylladb/issues/18786
Fixes a regression introduced in 6.0, so needs backport to 6.0 and 6.1
Closesscylladb/scylladb#20109
* github.com:scylladb/scylladb:
test/tablets: Test that reading tablets' mutations from MUTATION_FRAGMENTS works
replica/mutation_dump: enfore pinning of effective replication map
replica/mutation_dump: handle un-owned tokens (with tablets)
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