[lldb] [testsuite] TestReproducerAttach.py: Fix dependency on external symbol files

D55859 and D63339 prevented needless dependencies on system symbol
files. This testcase was checked-in afterwards and it brings back one
such unwanted dependency. Under some circumstances it may cause false
FAILs and/or excessive resource usage to run the testcase.

clang-format does not support .py so I have formatted it as I found most
compatible.

Also this is not a full testcase-style initialization, for example
--no-lldbinit ignores env("NO_LLDBINIT") setting which lldbtest.py does
implement:
  # If we spawn an lldb process for test (via pexpect), do not load the
  # init file unless told otherwise.
  if os.environ.get("NO_LLDBINIT") != "NO":
      self.lldbOption += " --no-lldbinit"

But this is what lldbpexpect.py does - it also ignores
env("NO_LLDBINIT"). Sure one could also fix lldbpexpect.py to unify the
initialization more with lldbtest.py but I find that outside of the
scope of this patch.

Differential Revision: https://reviews.llvm.org/D79649