Remove unused @rushstack/rush-sdk dependency from heft-webpack5-everything-test and heft-rspack-everything-test

Co-authored-by: dmichon-msft <26827560+dmichon-msft@users.noreply.github.com>

Author: Copilot

build-tests/heft-rspack-everything-test/package.json

@@ -19,7 +19,6 @@
     "@rushstack/heft-rspack-plugin": "workspace:*",
     "@rushstack/heft": "workspace:*",
     "@rushstack/node-core-library": "workspace:*",
-    "@rushstack/rush-sdk": "workspace:*",
     "@types/heft-jest": "1.0.1",
     "@types/node": "20.17.19",
     "eslint": "~9.37.0",

build-tests/heft-webpack5-everything-test/package.json

@@ -21,7 +21,6 @@
     "@rushstack/heft": "workspace:*",
     "@rushstack/module-minifier": "workspace:*",
     "@rushstack/node-core-library": "workspace:*",
-    "@rushstack/rush-sdk": "workspace:*",
     "@rushstack/webpack5-module-minifier-plugin": "workspace:*",
     "@types/heft-jest": "1.0.1",
     "@types/node": "20.17.19",