Update httpcomponents dependencies (#12871).

httpclient 4.1.2 -> 4.3.1, now directly from Maven central
httpcore 4.1.2 -> 4.3, now directly from Maven central
httpmime 4.1.2 -> 4.3.1, now directly from Maven central

Change-Id: I0056993edc1e14262da7697ed550b70cc2ed79c9