Drop the scripts base pin from every ct/ script (#17585)

ProxmoxVE is the engine's default scripts base as of community-scripts/core#76,
so the pin no longer changes anything.

.github/workflows/check-node-versions.yml

@@ -491,7 +491,7 @@ jobs:
           bash -c "\$(curl -fsSL "\$COMMUNITY_SCRIPTS_URL/ct/${slug}.sh")"
           \`\`\`
 
-          Both lines are needed — each script pins \`_CS_DEFAULT_URL\` to \`main\`, and that pin is what fills \`COMMUNITY_SCRIPTS_URL\` when it is unset.
+          Both lines are needed — without \`COMMUNITY_SCRIPTS_URL\` the engine takes the \`install/\` script from \`main\`.
 
           If the bump is wrong — upstream ships a newer Node than the app needs, or this script is deliberately held back — **close this PR**. It gets recorded on the drift report and this exact bump is not proposed again.
           PR_EOF

.github/workflows/pr-test-command.yml

@@ -111,10 +111,9 @@ jobs:
                 );
               }
               lines.push(
-                'Both lines are needed. Each script pins `_CS_DEFAULT_URL` to `main`, and that',
-                'pin is what fills `COMMUNITY_SCRIPTS_URL` when the variable is unset — so',
-                'curling the branch URL on its own gives you the `ct/` script from this PR and',
-                'the `install/` script from `main`. Frequently the one you meant to test.',
+                'Both lines are needed. Without `COMMUNITY_SCRIPTS_URL` the engine falls back to',
+                '`main`, so curling the branch URL on its own gives you the `ct/` script from',
+                'this PR and the `install/` script from `main`. Frequently the one you meant to test.',
                 '',
                 'The same command works on an Incus host: the engine detects the platform and',
                 'loads the matching backend, while the scripts still come from this branch.',