Improve error message when an SST file in MANIFEST is not found

[cbi42]

Summary: I got the following error message when an SST file is recorded in MANIFEST but is missing from the db folder.
It's confusing in two ways:

1. The part about file "./074837.ldb" which RocksDB will attempt to open only after ./074837.sst is not found.
2. The last part about "No such file or directory in file ./MANIFEST-074507" sounds like 074837.ldb is not found in manifest.

ldb --hex --db=. get some_key

Failed: Corruption: Corruption: IO error: No such file or directory: While open a file for random read: ./074837.ldb: No such file or directory in file ./MANIFEST-074507

Improving the error message a little bit:

Test plan: run the same command after this PR

Failed: Corruption: Corruption: IO error: No such file or directory: While open a file for random read: ./074837.sst: No such file or directory  The file ./MANIFEST-074507 may be corrupted.

[ajkr]

Thanks, this will save me some recurring explaining effort

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@cbi42 has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[cbi42]

Thanks for the review! Seems I forgot to import this one.

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@cbi42 merged this pull request in 854eb76.