ci: remove single value os matrix field from E2E jobs

Since the `os` matrix field only ever has a single value, there is no need
to include it in the matrix itself. This also shortens the display name
by removing the otherwise static value from each matrix job entry.

(cherry picked from commit 4cdc66b)

Author: clydin

.github/workflows/ci.yml

@@ -78,11 +78,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest]
         node: [20, 22, 24]
         subset: [esbuild, webpack]
         shard: [0, 1, 2, 3, 4, 5]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     steps:
       - name: Initialize environment
         uses: angular/dev-infra/github-actions/npm/checkout-and-setup-node@fabf48e542781bd9f18b1dd9dddfd5053cde77ac
@@ -132,11 +131,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [windows-2025]
         node: [22]
         subset: [esbuild, webpack]
         shard: [0, 1, 2, 3, 4, 5]
-    runs-on: ${{ matrix.os }}
+    runs-on: windows-2025
     steps:
       - name: Initialize environment
         uses: angular/dev-infra/github-actions/npm/checkout-and-setup-node@fabf48e542781bd9f18b1dd9dddfd5053cde77ac
@@ -160,11 +158,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest]
         node: [22]
         subset: [yarn, pnpm, bun]
         shard: [0, 1, 2]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     steps:
       - name: Initialize environment
         uses: angular/dev-infra/github-actions/npm/checkout-and-setup-node@fabf48e542781bd9f18b1dd9dddfd5053cde77ac
@@ -185,11 +182,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest]
         node: [22]
         subset: [esbuild, webpack]
         shard: [0, 1, 2, 3, 4, 5]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     steps:
       - name: Initialize environment
         uses: angular/dev-infra/github-actions/npm/checkout-and-setup-node@fabf48e542781bd9f18b1dd9dddfd5053cde77ac

.github/workflows/pr.yml

@@ -108,11 +108,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest]
         node: [22]
         subset: [esbuild, webpack]
         shard: [0, 1, 2, 3, 4, 5]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     steps:
       - name: Initialize environment
         uses: angular/dev-infra/github-actions/npm/checkout-and-setup-node@fabf48e542781bd9f18b1dd9dddfd5053cde77ac
@@ -178,11 +177,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest]
         node: [22]
         subset: [yarn, pnpm, bun]
         shard: [0, 1, 2]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     steps:
       - name: Initialize environment
         uses: angular/dev-infra/github-actions/npm/checkout-and-setup-node@fabf48e542781bd9f18b1dd9dddfd5053cde77ac
@@ -201,11 +199,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest]
         node: [22]
         subset: [esbuild, webpack]
         shard: [0, 1, 2, 3, 4, 5]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     steps:
       - name: Initialize environment
         uses: angular/dev-infra/github-actions/npm/checkout-and-setup-node@fabf48e542781bd9f18b1dd9dddfd5053cde77ac