Cleanup performance_test and test_benchmarks (cvxpy#2592)

* removing unused tests

* removing performance tests from setup

* Revert "removing unused tests"

This reverts commit 71c0feb.

* Revert "removing performance tests from setup"

This reverts commit 29b5ca5.

* adding minor change to README to test CI

* Revert "Revert "removing unused tests""

This reverts commit 3c41aec.

* Revert "Revert "removing performance tests from setup""

This reverts commit 94f02d4.

* Revert "adding minor change to README to test CI"

This reverts commit 5a63e8e.

* removing performance_tests from test_script

---------

Co-authored-by: William Zijie Zhang <william@gridmatic.com>

Author: Transurgeon

continuous_integration/test_script.sh

@@ -23,6 +23,4 @@ if [[ "$SINGLE_ACTION_CONFIG" == "True" ]]; then
     pytest cvxpy/tests --cov=cvxpy --cov-report xml:coverage.xml
 else
     pytest cvxpy/tests
-fi
-
-pytest cvxpy/performance_tests
+fi