Use max-parallel: 20 as asked by Apache Infra

Author: garydgregory

.github/workflows/codeql-analysis.yml

@@ -29,6 +29,7 @@ jobs:
       security-events: write
 
     strategy:
+      max-parallel: 20
       fail-fast: false
       matrix:
         language: [ 'java' ]

.github/workflows/maven.yml

@@ -30,6 +30,7 @@ jobs:
     runs-on: ubuntu-latest
     continue-on-error: ${{ matrix.experimental }}
     strategy:
+      max-parallel: 20
       matrix:
         java: [ 8, 11, 17, 21 ]
         experimental: [false]