chore: remove deprecated @angular/flex-layout dependency

@angular/flex-layout has been deprecated since Angular v15 and is no
longer maintained. The package was listed as a dependency in two
datagrid apps but was not actually imported or used anywhere in the
code. Removing it eliminates the unused deprecated dependency.

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Author: abalaster

examples/fdc3-chart-and-grid/js-datagrid/package.json

@@ -15,7 +15,6 @@
     "@angular/common": "21.1.5",
     "@angular/compiler": "21.1.5",
     "@angular/core": "21.1.5",
-    "@angular/flex-layout": "^15.0.0-beta.42",
     "@angular/forms": "21.1.5",
     "@angular/material": "21.1.5",
     "@angular/platform-browser": "21.1.5",

examples/js-chart-and-grid-messagerouter/js-datagrid/package.json

@@ -15,7 +15,6 @@
     "@angular/common": "21.1.5",
     "@angular/compiler": "21.1.5",
     "@angular/core": "21.1.5",
-    "@angular/flex-layout": "^15.0.0-beta.42",
     "@angular/forms": "21.1.5",
     "@angular/material": "21.1.5",
     "@angular/platform-browser": "21.1.5",