[lldb] Replace assertTrue(a == b, "msg") with assertEquals(a, b, "msg") in the test suite

Summary:
The error message from the construct `assertTrue(a == b, "msg") ` are nearly always completely useless for actually debugging the issue.
This patch is just replacing this construct (and similar ones like `assertTrue(a != b, ...)` with the proper call to assertEqual or assertNotEquals.

This patch was mostly written by a shell script with some manual verification afterwards:
```
lang=python
import sys

def sanitize_line(line):
  if line.strip().startswith("self.assertTrue(") and " == " in line:
    line = line.replace("self.assertTrue(", "self.assertEquals(")
    line = line.replace(" == ", ", ", 1)
  if line.strip().startswith("self.assertTrue(") and " != " in line:
    line = line.replace("self.assertTrue(", "self.assertNotEqual(")
    line = line.replace(" != ", ", ", 1)
  return line

for a in sys.argv[1:]:
  with open(a, "r") as f:
    lines = f.readlines()
  with open(a, "w") as f:
    for line in lines:
      f.write(sanitize_line(line))
```

Reviewers: labath, JDevlieghere

Reviewed By: labath

Subscribers: abidh, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D74475