test: update and clean some tests

Merged Félix Olart requested to merge fix/wrong-sip-syntax-in-tests-using-belle-sip into release/2.4

Updating linphone-sdk on master branch led to failed tests on our test suite (they changed the SIP parser from antlr to belr). This MR corrects the syntax in the erroneous raw SIP requests, so the corresponding tests can now execute successfully using belr.

Contributes to close FLEXISIP-371

Edited by Félix Olart

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