When the aggregate uses variables, we need to ensure that the
cache key correctly considers the current value of ALL those
variables. Otherwise we'll return incorrect results when
an expression is re-evaluated after changing the variable
value for the context.
Fixes use of aggregate function with @symbol_label in legends.
Fixes#58221
The original workaround was only supposed to apply to QList/
QVector of QVariantMaps. By replacing them all in sip we
break mapping of signals defined in c++ which are emitted
by Python code.
Fixes exceptions after running processing algorithms in Qt6
builds.
