Revert "make smtlib-model-format default for yices-smt2" #470

Job	Run time
ubuntu-latest\|debug\|--enable-mcsat\|CC=gcc CXX=g++	7m 57s
ubuntu-latest\|debug\|--enable-mcsat\|CC=clang CXX=clang++	8m 48s
ubuntu-latest\|debug\|--enable-thread-safety\|CC=gcc CXX=g++	5m 42s
ubuntu-latest\|debug\|--enable-thread-safety\|CC=clang CXX=clang++	4m 40s
ubuntu-latest\|release\|--enable-mcsat\|CC=gcc CXX=g++	6m 37s
ubuntu-latest\|release\|--enable-mcsat\|CC=clang CXX=clang++	5m 26s
ubuntu-latest\|release\|--enable-thread-safety\|CC=gcc CXX=g++	4m 0s
ubuntu-latest\|release\|--enable-thread-safety\|CC=clang CXX=clang++	3m 53s
ubuntu-latest\|gcov\|--enable-mcsat\|CC=gcc CXX=g++	8m 32s
ubuntu-latest\|debug\|--enable-thread-safety --enable-mcsat\|CC=gcc CXX=g++	11m 1s
	1h 6m 36s

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