qt: remove de_AT translation

Got too many complaints that is was unserious and written by trolls.
I have also removed the translation from transifex.
Fixes #4054 and #3918.

src/qt/Makefile.am

@@ -25,7 +25,6 @@ QT_TS = \
   locale/bitcoin_cs.ts \
   locale/bitcoin_cy.ts \
   locale/bitcoin_da.ts \
-  locale/bitcoin_de_AT.ts \
   locale/bitcoin_de.ts \
   locale/bitcoin_el_GR.ts \
   locale/bitcoin_en.ts \

src/qt/bitcoin.qrc

@@ -98,7 +98,6 @@
         <file alias="cs">locale/bitcoin_cs.qm</file>
         <file alias="cy">locale/bitcoin_cy.qm</file>
         <file alias="da">locale/bitcoin_da.qm</file>
-        <file alias="de_AT">locale/bitcoin_de_AT.qm</file>
         <file alias="de">locale/bitcoin_de.qm</file>
         <file alias="el_GR">locale/bitcoin_el_GR.qm</file>
         <file alias="en">locale/bitcoin_en.qm</file>