e1: highlight outdated extension versions (fix logic)

[NikolayS]

It is incorrect to compare installed_version with pg_extension.extversion, it should be compared with pg_available_extensions.default_version. It lead to incorrectly working actuality flag – at all times it was empty.

This commit fixes it. Also, available_extension column is removed – its logic was wrong from the very beginning.

Example:

• before fix:

      name        | installed_version | default_version | available_version | actuality
  --------------------+-------------------+-----------------+-------------------+-----------
  pg_stat_statements | 1.2               | 1.4             | 1.2               | 
  plpgsql            | 1.0               | 1.0             | 1.0               |
  (2 rows)

• after fix:

      name        | installed_version | default_version | actuality
  --------------------+-------------------+-----------------+-----------
  pg_stat_statements | 1.2               | 1.4             | OLD
  plpgsql            | 1.0               | 1.0             |
  (2 rows)