[ticket/10838] Updated RUNNING_TESTS.md

PHPBB3-10838
[ticket/10838] separate database used mentioned in unit tests

Separate database used for tests which is deleted each time
tests are run information is added to unit tests.

PHPBB3-10838
[ticket/10838] Fix missing data

PHPBB3-10838
[ticket/10838] Remove php 5.4 and builtin server references

PHPBB3-10838
[ticket/10838] Fix URL for wiki and remove irrelevant line

PHPBB3-10838
Merge remote-tracking branch 'dhruvgoel92/ticket/10838' into develop-olympus

* dhruvgoel92/ticket/10838:
  [ticket/10838] Fix URL for wiki and remove irrelevant line
  [ticket/10838] Remove php 5.4 and builtin server references
  [ticket/10838] Fix missing data
  [ticket/10838] separate database used mentioned in unit tests
  [ticket/10838] Updated RUNNING_TESTS.md