Put retrieveGaData test1 = new retrieveGAdata(); after Test.setMock. That's the only line of code that could execute a callout as far as I can see.

Put retrieveGaData test1 = new retrieveGAdata(); after Test.setMock. That's the only line of code that could execute a callout as far as I can see.

public static testmethod  void testsaveDataToSF()
{
    // other setup
    Test.setMock(HttpCalloutMock.class, multiCalloutMock);
    retrieveGaData test1 = new retrieveGAdata();
}