perf: Avoid scanning installed packages when MCP SDK is not installed (#6769)

When mcp SDK is not installed, module-level package_version('mcp') at
the top of sentry_sdk/integrations/mcp.py scans every installed
distribution, slowing sentry_sdk.init() by ~200ms in environments
with hundreds of packages.

Move the call below the 	ry/except ImportError guard so it only runs
when import mcp succeeds. Environments without mcp skip the scan
entirely.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mangodxd

sentry_sdk/integrations/mcp.py

@@ -20,14 +20,14 @@
 from sentry_sdk.tracing_utils import has_span_streaming_enabled
 from sentry_sdk.utils import nullcontext, package_version, safe_serialize
 
-MCP_PACKAGE_VERSION = package_version("mcp")
-
 try:
     from mcp.server.lowlevel import Server
     from mcp.server.streamable_http import (
         StreamableHTTPServerTransport,
     )
 
+    MCP_PACKAGE_VERSION = package_version("mcp")
+
     if MCP_PACKAGE_VERSION and MCP_PACKAGE_VERSION < (2, 0, 0):
         from mcp.server.lowlevel.server import (  # type: ignore[attr-defined]
             request_ctx,