Revert "make smtlib-model-format default for yices-smt2" #467

Job	Run time
ubuntu-latest\|debug\|--enable-mcsat\|CC=gcc CXX=g++	8m 12s
ubuntu-latest\|debug\|--enable-mcsat\|CC=clang CXX=clang++	8m 40s
ubuntu-latest\|debug\|--enable-thread-safety\|CC=gcc CXX=g++	4m 8s
ubuntu-latest\|debug\|--enable-thread-safety\|CC=clang CXX=clang++	4m 37s
ubuntu-latest\|release\|--enable-mcsat\|CC=gcc CXX=g++	5m 13s
ubuntu-latest\|release\|--enable-mcsat\|CC=clang CXX=clang++	5m 56s
ubuntu-latest\|release\|--enable-thread-safety\|CC=gcc CXX=g++	2m 29s
ubuntu-latest\|release\|--enable-thread-safety\|CC=clang CXX=clang++	2m 42s
ubuntu-latest\|gcov\|--enable-mcsat\|CC=gcc CXX=g++	8m 17s
ubuntu-latest\|debug\|--enable-thread-safety --enable-mcsat\|CC=gcc CXX=g++	7m 56s
	58m 10s

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