[improvement](test) add --conf option for run-regression-test.sh for custom config file

[xiaokang]

Proposed changes

Developers need to change port in regression-test/conf/regression-conf.groovy to run regression test locally if they share the same machine and use different ports. It's not convenient may lead to mistake commit for regression-conf.groovy.

This PR add --conf option for run-regression-test.sh for custom config file. It can be used as follows:

sh run-regression-test.sh --run --conf my-regression-conf.groovy -d tpch_sf1_p0

Problem summary

Describe your changes.

Checklist(Required)

1. Does it affect the original behavior:
   • Yes
   • No
   • I don't know
2. Has unit tests been added:
   • Yes
   • No
   • No Need
3. Has document been added or modified:
   • Yes
   • No
   • No Need
4. Does it need to update dependencies:
   • Yes
   • No
5. Are there any changes that cannot be rolled back:
   • Yes (If Yes, please explain WHY)
   • No

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[github-actions]

sh-checker report

To get the full details, please check in the job output.

shellcheck errors

'shellcheck ' returned error 1 finding the following syntactical issues:

----------

In run-regression-test.sh line 131:
    echo "Using custom config file $CONFIG_FILE"
                                   ^----------^ SC2250 (style): Prefer putting braces around variable references even when not strictly required.

Did you mean: 
    echo "Using custom config file ${CONFIG_FILE}"

For more information:
  https://www.shellcheck.net/wiki/SC2250 -- Prefer putting braces around vari...
----------

You can address the above issues in one of three ways:
1. Manually correct the issue in the offending shell script;
2. Disable specific issues by adding the comment:
  # shellcheck disable=NNNN
above the line that contains the issue, where NNNN is the error code;
3. Add '-e NNNN' to the SHELLCHECK_OPTS setting in your .yml action file.

shfmt errors

'shfmt ' found no issues.

[yiguolei]

LGTM