Fix syntax and semantic errors in kdump remote feature

[arista-hpandya]

Fixes #4115

What I did

Fixed bugs in the upstream kdump remote SSH feature:

1. Fixed regex patterns in sed commands to prevent unintended replacements
2. Removed redundant SSH_KEY operations
3. Fixed typo: options.verbos → options.verbose
4. Simplified SSH path update logic by removing unnecessary comparison check
5. Updated help text for --remote flag to better reflect its functionality
6. Changed delimiter in write_ssh_path() sed command from / to | to handle paths correctly

How I did it

1. Fixed sed regex patterns:

• Added ^ anchor to sed patterns (s/#SSH/SSH/ → s/^#SSH/SSH/) to ensure only lines starting with #SSH are matched, preventing false matches in comments or other parts of the configuration file

2. Removed redundant SSH_KEY operations:

• The SSH_KEY line doesn't need separate toggling since it's controlled by the same sed command. Removed duplicate sed commands for SSH_KEY in both write_kdump_remote() and cmd_kdump_remote() functions

3. Fixed typo:

• Corrected options.verbos to options.verbose in the main argument parsing section

4. Simplified SSH path update:

• Removed unnecessary check comparing current SSH path with new path in cmd_kdump_ssh_path(). The function now always writes the path when provided, simplifying the logic

5. Updated sed delimiter:

• Changed delimiter in write_ssh_path() from / to | (s/#*SSH_KEY=.*/ → s|#*SSH_KEY=.*|) to properly handle SSH key paths that may contain forward slashes

6. Updated tests:

• Modified unit tests to reflect the simplified implementation
• Removed obsolete test case test_cmd_kdump_ssh_path_no_update that tested the removed comparison logic

How to verify it

Initial state:
Manually uncommented SSH and SSH_KEY config in /etc/default/kdump-tools
After reboot we expect the hostcfgd service to start and uncomment it because KDUMP|config|remote is false

After reboot:
#SSH="user@localhost"
#SSH_KEY="/a/b/c"

>>> root@device:~# sonic-kdump-config --ssh_string "trial@localhost"
SSH string updated. Changes will take effect after the next reboot.
>>> root@device:~# sonic-kdump-config --ssh_path "/var/"
SSH path updated. Changes will take effect after reboot.

State of /etc/default/kdump-tools:
SSH="trial@localhost"
SSH_KEY="/var/"

>>> root@device:~# sonic-db-cli CONFIG_DB HGETALL "KDUMP|config"
{'enabled': 'true', 'memory': '0M-2G:256M,2G-4G:320M,4G-8G:384M,8G-:448M', 'num_dumps': '3', 'remote': 'false', 'ssh_string': 'user@localhost', 'ssh_path': '/a/b/c'}
>>> root@device:~# sonic-kdump-config --remote 

State of /etc/default/kdump-tools:
#SSH="trial@localhost"
#SSH_KEY="/var/"

After another reboot:

State of /etc/default/kdump-tools:
#SSH="trial@localhost"
#SSH_KEY="/var/"

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[judyjoseph]

LGTM

[Copilot]

Pull request overview

This PR fixes several syntax and semantic errors in the kdump remote SSH feature. The changes correct regex patterns to prevent unintended replacements, remove redundant operations, fix a typo, and simplify logic for better maintainability.

Key Changes:

• Fixed sed regex patterns by adding ^ anchors to match only at line start, preventing false matches in comments or other configuration sections
• Corrected typo options.verbos → options.verbose in command-line argument handling
• Changed sed delimiter from / to | in SSH path updates to properly handle paths containing forward slashes

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
scripts/sonic-kdump-config	Fixed sed regex patterns with ^ anchors, removed redundant SSH_KEY sed commands (single command now handles both SSH and SSH_KEY lines), fixed typo in argument parsing, simplified SSH path update logic, and changed sed delimiter to handle paths correctly
tests/sonic_kdump_config_test.py	Updated test assertions to verify single sed command execution instead of two, corrected expected sed patterns to include ^ anchors and pipe delimiters, and removed obsolete test case for comparison logic that was simplified

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[arista-hpandya]

@rlhui @arlakshm Can we merge this PR? All check has passed and the code has been reviewed.