rules: correct MITRE tags on sensitive-path read and reverse-shell rules

Apply @leogr's review on two of the tags added in the previous commit.

- 'Deny reading sensitive paths' matched reads of known credential
  locations (~/.ssh/, cloud credential dirs, .env). That is Credential
  Access, not Discovery, so retag from
  mitre_t1083_file_and_directory_discovery to
  mitre_t1552_unsecured_credentials, matching the sibling
  credential-access rules.

- 'Deny reverse shell via Bash' matched shell redirection/exec
  (/dev/tcp, nc -e, socat exec:); it never inspects ports, so
  mitre_t1571_non_standard_port did not apply. Drop it and keep
  mitre_t1059_command_and_scripting_interpreter, matching upstream
  Falco's reverse-shell tagging.

Tags-only, additive: no condition, macro, field, or verdict-tag change;
rule count unchanged (60); validated with falco 0.44.0 --validate
(Ok, warning count unchanged at 117).

Signed-off-by: Adam Lin <adam@agentthreatrule.org>

Author: eeee2345

rules/default/coding_agents_rules.yaml

@@ -228,7 +228,7 @@
     Falco blocked reading %tool.real_file_path because it is a sensitive path
   priority: CRITICAL
   source: coding_agent
-  tags: [coding_agent_deny, mitre_t1083_file_and_directory_discovery]
+  tags: [coding_agent_deny, mitre_t1552_unsecured_credentials]
 
 - rule: Deny writing to sensitive paths
   desc: >
@@ -1270,7 +1270,7 @@
     Falco blocked a reverse shell command (%tool.input_command)
   priority: CRITICAL
   source: coding_agent
-  tags: [coding_agent_deny, mitre_t1059_command_and_scripting_interpreter, mitre_t1571_non_standard_port]
+  tags: [coding_agent_deny, mitre_t1059_command_and_scripting_interpreter]
 
 - rule: Deny cloud metadata service access via Bash
   desc: >