ProjectExplorer: Remove Run{Control,Configuration}::abi

Unused now, and arguably not a valid concept anymore.
A run control may consist of different runworkers,
'operating' on different systems.

Since the removed RunConfiguration::abi() implementation uses
only public Target ABI, user code could revive that locally
in case it was needed again.

Change-Id: I658c6e88b4a1aec18bf4de91fc86230552bc0710
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/qmlprojectmanager/qmlprojectrunconfiguration.cpp

@@ -374,13 +374,6 @@ QString QmlProjectRunConfiguration::commandLineArguments() const
     return args;
 }
 
-Abi QmlProjectRunConfiguration::abi() const
-{
-    Abi hostAbi = Abi::hostAbi();
-    return Abi(hostAbi.architecture(), hostAbi.os(), hostAbi.osFlavor(),
-               Abi::RuntimeQmlFormat, hostAbi.wordWidth());
-}
-
 void QmlProjectRunConfiguration::updateEnabledState()
 {
     bool qmlFileFound = m_mainQmlFileAspect->isQmlFilePresent();