fix: add slash after generated region_dir

[waynexia]

I hereby agree to the terms of the GreptimeDB CLA

What's changed and what's your intention?

MySQL [(none)]> show tables;
+---------+
| Tables  |
+---------+
| numbers |
| scripts |
| t       |
+---------+
3 rows in set (0.013 sec)

MySQL [(none)]> drop table t;
Query OK, 1 row affected (0.004 sec)

MySQL [(none)]> show tables;
+---------+
| Tables  |
+---------+
| numbers |
| scripts |
+---------+
2 rows in set (0.001 sec)

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.

Refer to a related PR or issue link (optional)

closes #2457

[fengjiachun]

@waynexia The unit test failed

[WenyXu]

verbose: We need always keep in mind all directory paths should end with /

[evenyag]

We still need to sanitize the dir in mito2, as I mentioned in #2457 (comment)

[waynexia]

We still need to sanitize the dir in mito2, as I mentioned in #2457 (comment)

All region dir generated by this function will end with slash. There is no second method to concat it. Unless you direct give a random string as dir, which is neither possible nor viable to validate them all.

[killme2008]

I think we can normalize the path when creating or opening regions. Then it can cover all the cases using the normalized one instead of the raw path.

[codecov]

Codecov Report

Merging #2463 (bb5123b) into develop (580d11b) will decrease coverage by 0.37%.
The diff coverage is 100.00%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2463      +/-   ##
===========================================
- Coverage    84.83%   84.46%   -0.37%     
===========================================
  Files          726      726              
  Lines       114995   114995              
===========================================
- Hits         97551    97130     -421     
- Misses       17444    17865     +421     

[evenyag]

This is related to the behavior of mito2. If region_dir must end with /, then mito2 should return an error, or sanitize the directory. I'll add this check later.