Remove the isResumable parameter from MultiIndexBlock::persistResumeState and
MultiIndexBlock::abortWithoutCleanup, since the value is now stored on the
MultiIndexBlock itself via setIsResumable().

SERVER-125654 made IndexBuildsManager::setUpIndexBuild call
builder->setIsResumable(options.isResumable), so the _isResumable member is
populated from the same source (replState->isResumable()) that callers pass into
persistResumeState / abortWithoutCleanup. The parameter is now redundant.