AIDEGen: In finding modules step, removing superfluous printed info.

1. When check if the module name that user provided is valid, aidegen show too
   many redundant info to user.
2. Fix a pylint case, R1720: Unnecessary "else" after "raise".

Bug: 132301867
Test: 1. aidegen-dev NewTestOne4
      2. Following info should not print:
         - The path NewOneTest4 doesn't exist. We should rebuild
           module-info.json file for it.
      3. Follwing error info should print once only.
         - The path NewOneTest4 doesn't exist.

Change-Id: I77541a27bcbccb4a39b6b0ce3e4a64dd9d4ae707