Misc code improvements: override, destructor, small mistakes

[tvami]

I am updating ldmx-sw, here are the details.

What are the issues that this addresses?

This is part of #1176
Specifically running

just configure  -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_C_COMPILER=clang
just build 

Check List

• I successfully compiled ldmx-sw with my developments
• I ran my developments and the following shows that they are successful.
  Errors/warnings are gone, except for Static analysis meta-issue #1176 (comment)

I moved every instances of final override to override now in bb2eef4 based on the guidelines in https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rh-override

[EinarElen]

The reasoning is here :)

https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rh-override

[tvami]

I moved every instances of final override to override now in bb2eef4