Switch SDK rollForward from disable to patch for automatic servicing updates (#4364)

* Switch SDK rollForward from disable to patch

Allow automatic roll-forward within the 10.0.3xx feature band so that
servicing patches (e.g. security fixes like 10.0.301) are picked up by
CI agents and developers without requiring a dedicated PR for each bump.

The base version remains 10.0.300 — this is the minimum required SDK.
Any installed 10.0.3xx patch will be used automatically.

Updated both global.json files:
- /global.json (repo root)
- /tools/PackageCompatibility/global.json

* Re-worded SDK comment.

Author: paulmedynski

global.json

@@ -4,8 +4,9 @@
     // We currently require the .NET 10 SDK to build and test the project.
     "version": "10.0.300",
 
-    // Lock to the above version so that we can control when we take breaking sdk changes.
-    "rollForward": "disable",
+    // Allow roll-forward within the 10.0.3xx feature band so servicing patches
+    // are picked up automatically without requiring a PR for each bump.
+    "rollForward": "patch",
 
     // Do not allow pre-release versions.
     //

tools/PackageCompatibility/global.json

@@ -7,9 +7,9 @@
   "sdk": {
     // global.json lookup stops at the nearest file and does not merge with the repo-root file.
     // This subtree therefore needs to repeat the root SDK settings so commands run from
-    // tools/PackageCompatibility keep using the same pinned SDK behavior.
+    // tools/PackageCompatibility keep using the same SDK behavior.
     "version": "10.0.300",
-    "rollForward": "disable",
+    "rollForward": "patch",
     "allowPrerelease": false
   }
 }