fix: support dynamic install agent multi-times with different agent directory

[lilai23]

What type of PR is this?

Bug

What this PR does / why we need it?

Currently when users dynamic install agent at the second time, the directory of new agent can not be a custom path. So this PR aims to fix this issue

Which issue(s) this PR fixes？

Fixes #

Does this PR introduce a user-facing change?

No

Checklist

• Make sure there is a GitHub_issue related with this PR before you start working on it.
• Make sure you have squashed your change to one single commit.
• GitHub Actions works fine in this PR.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...src/main/java/io/sermant/core/utils/FileUtils.java	60.00%	2 Missing ⚠️
...c/main/java/io/sermant/core/AgentCoreEntrance.java	0.00%	1 Missing ⚠️

Flag	Coverage Δ	Complexity Δ
unittests	43.88% <50.00%> (-0.02%)	181.00 <0.00> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ	Complexity Δ
...in/java/io/sermant/core/common/CommonConstant.java	0.00% <ø> (ø)	0.00 <0.00> (ø)
...c/main/java/io/sermant/core/AgentCoreEntrance.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...src/main/java/io/sermant/core/utils/FileUtils.java	11.70% <60.00%> (ø)	0.00 <0.00> (ø)

... and 14 files with indirect coverage changes