RDKB-64639 Fix resource leaks in cci process

[pavithrasundaravadivel]

Impacted Platforms:
TCXB7, TCXB8

Reason for change: Properly close the FD's before return

Test Procedure: Run any cci test and check for the FD count before/after test

Risks: None

Priority: P1

Signed-off-by:Pavithra_Sundaravadivel@comcast.com

[Copilot]

Pull request overview

This PR addresses file descriptor/resource leaks in the CCI test execution paths by ensuring opened pipes/files and libpcap dump handles are properly closed on early returns and after use.

Changes:

• Close the gateway performance result file before aborting on unsupported TopCmdOptions.
• Add missing pclose()/fclose() calls on error paths in the command test step to prevent leaked pipes/files.
• Close libpcap dump handles (pcap_dump_close) after writing/flush in both internal and external-agent pcap creation flows.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/tests/wlan_emu_test_param_gateway_performance.cpp	Closes the opened result FILE* before returning on invalid command option.
src/tests/wlan_emu_test_param_command.cpp	Ensures popen() pipes and optional capture files are closed on additional error paths.
src/messages/wlan_emu_msg.cpp	Adds pcap_dump_close() to release the dumper handle after writing the pcap.
src/external_agent_cci/wlan_ext_emu_test_step_params.cpp	Adds pcap_dump_close() to release the dumper handle after writing the pcap.

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