fix package.json and yarn.lock issues (#21006)

* build: undo yarn.lock changes from 5f81d04

These changes were accidentally brought in from master branch and
include an update to scss-bundle that causes a massive size regression
in our sass bundle.

* build: update @angular-devkit/build-optimizer to rc3

Author: mmalerba

package.json

@@ -69,7 +69,7 @@
     "zone.js": "~0.10.3"
   },
   "devDependencies": {
-    "@angular-devkit/build-optimizer": "^0.1100.0-rc.2",
+    "@angular-devkit/build-optimizer": "^0.1100.0-rc.3",
     "@angular-devkit/core": "^11.0.0-rc.3",
     "@angular-devkit/schematics": "^11.0.0-rc.3",
     "@angular/bazel": "^11.0.0-rc.3",