CHICAGO — Aldermen blocked a measure Thursday to place a symbolic question on the March primary ballot asking voters whether to end Chicago’s status as a sanctuary city, the likely end to a monthslong saga driven by opponents of Mayor Brandon Johnson seeking to take a stand against his response to the migrant crisis. In a 31-16 vote, the City Council sided with Johnson in rejecting a motion to debate whether to include a nonbinding referendum on the ballot asking “Should the City of Chicago limit its designation as a Sanctuary City by placing spending limits on its public funding?” The vote ca…