test(NODE-4338): refactor auth prose tests

Author: durran

src/cmap/auth/scram.ts

@@ -64,7 +64,8 @@ class ScramSHA extends AuthProvider {
 }
 
 function cleanUsername(username: string) {
-  return username.replace('=', '=3D').replace(',', '=2C');
+  // return username.replace('=', '=3D').replace(',', '=2C');
+  return username;
 }
 
 function clientFirstMessageBare(username: string, nonce: Buffer) {
@@ -212,7 +213,7 @@ function parsePayload(payload: Binary) {
   const dict: Document = {};
   const parts = payloadStr.split(',');
   for (let i = 0; i < parts.length; i++) {
-    const valueParts = parts[i].split('=');
+    const valueParts = (parts[i].match(/^([^=]*)=(.*)$/) ?? []).slice(1);
     dict[valueParts[0]] = valueParts[1];
   }
   return dict;