LineageParts: res: Delete duplicated and unused strings

The resource 'string/status_bar_icons_title' is defined twice, as seen while
compiling with AAPT2:

  packages/apps/LineageParts/res/values-af/strings.xml:427: error: duplicate value for resource 'string/status_bar_icons_title' with config 'af'.
  packages/apps/LineageParts/res/values-af/strings.xml:389: error: resource previously defined here.

Additionally, the resource 'string/status_bar_icons_summary' is not used anywhere,
and has the same content as 'string/status_bar_system_icons_summary'.

Change-Id: I896961dd4b24dd1b67ae7764ef211b4748403f2c