[ci-bitrise] Remove manage-ios-code-signing for good — no platform override exists

Same failure again with platform: iOS set. Unlike xcode-archive@5's error
('Define the platform step input manually to avoid this phase in the
future'), this step's error gives no such hint — it has no override.
Confirmed twice now: this step cannot run on a target with
SUPPORTED_PLATFORMS = iphoneos iphonesimulator macosx. Back to relying
on xcode-archive@5's own automatic_code_signing: api-key alone.

bitrise.yml

@@ -105,15 +105,6 @@ workflows:
             - content: |
                 cd $BITRISE_SOURCE_DIR/Darwin
                 agvtool new-version -all $BITRISE_BUILD_NUMBER
-      - manage-ios-code-signing@2:
-          inputs:
-            - distribution_method: app-store
-            - project_path: $BITRISE_PROJECT_PATH
-            - scheme: $BITRISE_SCHEME
-            # SDKROOT = auto on this target (Skip's multi-platform build)
-            # breaks the step's own platform auto-detection — pin it,
-            # same fix as xcode-archive@5 below.
-            - platform: iOS
       - xcode-archive@5:
           inputs:
             - project_path: $BITRISE_PROJECT_PATH
@@ -158,12 +149,6 @@ workflows:
             - content: |
                 cd $BITRISE_SOURCE_DIR/Darwin
                 agvtool new-version -all $BITRISE_BUILD_NUMBER
-      - manage-ios-code-signing@2:
-          inputs:
-            - distribution_method: app-store
-            - project_path: $BITRISE_PROJECT_PATH
-            - scheme: $BITRISE_SCHEME
-            - platform: iOS
       - xcode-archive@5:
           inputs:
             - project_path: $BITRISE_PROJECT_PATH