This is an addition to #11039, which cleans up rdbLoad* related errno. Remove the
errno print from the outer message (may be invalid since errno may have been overwritten).

Our aim should be the code that detects the error and knows which system call
triggered it, is the one to print errno, and not the code way up above (in some cases
a result of a logical error and not a system one).

Remove the code to update errno in rdbLoadRioWithLoadingCtx, signature check
and the rdb version check, in these cases, we do print the error message.
The caller dose not have the specific logic for handling EINVAL.

Small fix around rdb-preamble AOF: A truncated RDB is considered a failure,
not handled the same as a truncated AOF file.

The reason we do this is because in redis#11036, we added error
log message when failing to open RDB file for reading.
In loadDdataFromDisk we call rdbLoad and also check errno,
now the logging corrupts errno (reported in alpine daily).

It is not safe to rely on errno as we do today, so we change
the return value of rdbLoad function to enums, like we have
when loading an AOF.

This is an addition to redis#11039, which cleans up rdbLoad* related errno. Remove the
errno print from the outer message (may be invalid since errno may have been overwritten).

Our aim should be the code that detects the error and knows which system call
triggered it, is the one to print errno, and not the code way up above (in some cases
a result of a logical error and not a system one).

Remove the code to update errno in rdbLoadRioWithLoadingCtx, signature check
and the rdb version check, in these cases, we do print the error message.
The caller dose not have the specific logic for handling EINVAL.

Small fix around rdb-preamble AOF: A truncated RDB is considered a failure,
not handled the same as a truncated AOF file.