Replace vendor MathJax with NPM package, upgrade to 2.7.9 (#3702)

* Replace vendor MathJax with NPM package, upgrade to 2.7.9

* Disable fast-preview feature in Mathjax

GitOrigin-RevId: e3ef1dbabae1da7c359e370a2c491a4214841c76

services/web/package-lock.json

@@ -19550,6 +19550,12 @@
       "integrity": "sha512-6qE4B9deFBIa9YSpOc9O0Sgc43zTeVYbgDT5veRKSlB2+ZuHNoVVxA1L/ckMUayV9Ay9y7Z/SZCLcGteW9i7bg==",
       "dev": true
     },
+    "mathjax": {
+      "version": "2.7.9",
+      "resolved": "https://registry.npmjs.org/mathjax/-/mathjax-2.7.9.tgz",
+      "integrity": "sha512-NOGEDTIM9+MrsqnjPEjVGNx4q0GQxqm61yQwSK+/5S59i26wId5IC5gNu9/bu8+CCVl5p9G2IHcAl/wJa+5+BQ==",
+      "dev": true
+    },
     "md5": {
       "version": "2.3.0",
       "resolved": "https://registry.npmjs.org/md5/-/md5-2.3.0.tgz",
@@ -20055,7 +20061,7 @@
     },
     "mkdirp": {
       "version": "0.5.1",
-      "resolved": false,
+      "resolved": "",
       "integrity": "sha512-SknJC52obPfGQPnjIkXbmA6+5H15E+fR+E4iR2oQ3zzCLbd7/ONua69R/Gw7AgkTLsRG+r5fzksYwWe1AgTyWA==",
       "requires": {
         "minimist": "0.0.8"