fix(bazel): Make sure only single copy of @angular/bazel is installed (#30072)

When `ng add` is invoked independently of `ng new`, a node installation
of `@angular/bazel` is performed by the CLI before invoking the
schematic. This step appends `@angular/bazel` to the `dependencies`
section of `package.json`. The schematics then appends the same package
to `devDependencies`.

This leads to the warning:

```
warning package.json: "dependencies" has dependency "@angular/bazel" with
range "^8.0.0-beta.13" that collides with a dependency in "devDependencies"
of the same name with version "~8.0.0-beta.12"
```

PR Close #30072

packages/bazel/src/schematics/utility/json-utils.ts

@@ -40,7 +40,7 @@ export function removeKeyValueInAstObject(
       const start = prop.start.offset;
       const end = prop.end.offset;
       let length = end - start;
-      const match = content.slice(end).match(/[,\s]+/);
+      const match = content.slice(end).match(/^[,\s]+/);
       if (match) {
         length += match.pop() !.length;
       }