chore!: allow coder MCP tools to not be injected (#20713)

Currently, when AI Bridge is enabled AND the `oauth2` and
`mcp-server-http` experiments are enabled we inject Coder's MCP tools
into all intercepted AI Bridge requests.

This PR introduces a config to control this behaviour.

**NOTE:** this is a backwards-incompatible change; previously these
tools would be injected automatically, now this setting will need to be
explicitly enabled.

---------

Signed-off-by: Danny Kopping <danny@coder.com>

cli/testdata/coder_server_--help.golden

@@ -81,6 +81,11 @@ OPTIONS:
           check is performed once per day.
 
 AIBRIDGE OPTIONS: 
+      --aibridge-inject-coder-mcp-tools bool, $CODER_AIBRIDGE_INJECT_CODER_MCP_TOOLS (default: false)
+          Whether to inject Coder's MCP tools into intercepted AI Bridge
+          requests (requires the "oauth2" and "mcp-server-http" experiments to
+          be enabled).
+
       --aibridge-anthropic-base-url string, $CODER_AIBRIDGE_ANTHROPIC_BASE_URL (default: https://api.anthropic.com/)
           The base URL of the Anthropic API.
 

cli/testdata/server-config.yaml.golden

@@ -747,3 +747,7 @@ aibridge:
   # https://docs.claude.com/en/docs/claude-code/settings#environment-variables.
   # (default: global.anthropic.claude-haiku-4-5-20251001-v1:0, type: string)
   bedrock_small_fast_model: global.anthropic.claude-haiku-4-5-20251001-v1:0
+  # Whether to inject Coder's MCP tools into intercepted AI Bridge requests
+  # (requires the "oauth2" and "mcp-server-http" experiments to be enabled).
+  # (default: false, type: bool)
+  inject_coder_mcp_tools: false