Drone: Remove CI builds for Qt 5.7 and 5.8

Housekeeping and the new 2.7 Tray builds need at least Qt 5.9

Signed-off-by: Michael Schuster <michael@schuster.ms>

.drone.yml

@@ -1,78 +1,4 @@
 kind: pipeline
-name: qt-5.7
-
-steps:
-- name: build and test
-  image: nextcloudci/client-5.7:client-5.7-4
-  commands:
-    # Install QtKeyChain
-    - /bin/bash -c "
-      source /opt/qt57/bin/qt57-env.sh &&
-      cd /tmp &&
-      git clone https://github.com/frankosterfeld/qtkeychain.git &&
-      cd qtkeychain &&
-      git checkout v0.9.1 &&
-      mkdir build &&
-      cd build &&
-      cmake ../ &&
-      make &&
-      make install"
-    # Build client
-    - /bin/bash -c "
-      source /opt/qt57/bin/qt57-env.sh &&
-      mkdir build &&
-      cd build &&
-      cmake -D NO_SHIBBOLETH=1 -DBUILD_UPDATER=ON -DCMAKE_BUILD_TYPE=Debug -DUNIT_TESTING=1 -DSANITIZE_ADDRESS=ON ../ &&
-      make &&
-      useradd -m -s /bin/bash test &&
-      chown -R test:test . &&
-      su -c 'ASAN_OPTIONS=detect_leaks=0 ctest --output-on-failure' test"
-trigger:
-  branch:
-    - master
-  event:
-    - pull_request
-    - push
-
----
-kind: pipeline
-name: qt-5.8
-
-steps:
-- name: build and test
-  image: nextcloudci/client-5.8:client-5.8-4
-  commands:
-    # Install QtKeyChain
-    - /bin/bash -c "
-      source /opt/qt58/bin/qt58-env.sh &&
-      cd /tmp &&
-      git clone https://github.com/frankosterfeld/qtkeychain.git &&
-      cd qtkeychain &&
-      git checkout v0.9.1 &&
-      mkdir build &&
-      cd build &&
-      cmake ../ &&
-      make &&
-      make install"
-    # Build client
-    - /bin/bash -c "
-      source /opt/qt58/bin/qt58-env.sh &&
-      mkdir build &&
-      cd build &&
-      cmake -D NO_SHIBBOLETH=1 -DBUILD_UPDATER=ON -DCMAKE_BUILD_TYPE=Debug -DUNIT_TESTING=1 -DSANITIZE_ADDRESS=ON  ../ &&
-      make &&
-      useradd -m -s /bin/bash test &&
-      chown -R test:test . &&
-      su -c 'ASAN_OPTIONS=detect_leaks=0 ctest --output-on-failure' test"
-trigger:
-  branch:
-    - master
-  event:
-    - pull_request
-    - push
-
----
-kind: pipeline
 name: qt-5.9
 
 steps: