pin npm version for unit tests on node 22

Author: tadjik1

.evergreen/config.yml

@@ -1994,6 +1994,8 @@ tasks:
           updates:
             - {key: NODE_LTS_VERSION, value: '22'}
       - func: install dependencies
+        vars:
+          NPM_VERSION: 11.11.1
       - func: run unit tests
   - name: run-unit-tests-node-24
     tags:

.evergreen/generate_evergreen_tasks.js

@@ -485,7 +485,9 @@ const unitTestTasks = Array.from(
           updateExpansions({
             NODE_LTS_VERSION
           }),
-          { func: 'install dependencies' },
+          parseInt(NODE_LTS_VERSION, 10) === 22
+            ? { func: 'install dependencies', vars: { NPM_VERSION: '11.11.1' } }
+            : { func: 'install dependencies' },
           { func: 'run unit tests' }
         ]
       };