fix: parse normalized snapshotID

[mdutka-dell]

Description

• bug fixing connected with parsing normalized snapshotID
• writing additional unit tests

GitHub Issues

List the GitHub issues impacted by this PR:

GitHub Issue #
dell/csm#1104

Checklist:

• I have performed a self-review of my own code to ensure there are no formatting, vetting, linting, or security issues
• I have verified that new and existing unit tests pass locally with my changes
• I have not allowed coverage numbers to degenerate
• I have maintained at least 90% code coverage
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Backward compatibility is not broken

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also list any relevant details for your test configuration

• Unit tests

1) Package csi-powerscale/service
363 scenarios (363 passed)
1915 steps (1915 passed)
1m40.302991248s
godog finished
=== RUN   TestMkdirCreateDir
time="2024-02-14T05:21:45-05:00" level=debug   msg="created directory" file="/home/gosia/repos/csi-powerscale/service/mount.go:201"
--- PASS: TestMkdirCreateDir (0.00s)
=== RUN   TestMkdirExistingDir
--- PASS: TestMkdirExistingDir (0.00s)
=== RUN   TestMkdirExistingFile
--- PASS: TestMkdirExistingFile (0.00s)
PASS
coverage: 79.2% of statements
status 0
ok      github.com/dell/csi-isilon/v2/service   100.421s

2) Package csi-powerscale/common/utils
PASS
coverage: 45.9% of statements
ok      github.com/dell/csi-isilon/v2/common/utils      0.609s

[gallacher]

Please link this PR to a GitHub issue. Thanks.

[cbartoszDell]

lgtm

[shefali-malhotra]

LGTM