Update the not_allowed test case for QtDA

Have test case which generally uses accounts that will not allow installing the QtDA, usually the opensource account but there is exeption for super LTS reelase. To do that modify the existing test case suite_digital_advertising\tst_oss_qtda_not_allowed:

• rename to tst_qtda_not_allowed
• test has to decide from two different accounts which one to use, depending on which Qt version is used, so only test with one of the accounts:

• 5.15.0->5.15.2	Use the regular Opensource account, shared.get_account_obj(shared.get_account("Opensource"))
  5.15.3->5.15.14	Test is skipped (LTS mode, there is no opensource content available at all) [*]
  5.15.15->	super LTS (use is_feature.is_super_lts()) use regular account which doesn't have the Qt6Eligible feature: shared.get_account_obj(shared.get_account("ad_qtda_noqt6"))
  6.0.0->6.2.4	Use regular opensource account (see above)
  6.2.5->6.2.x	Test is skipped (LTS mode, there is no opensource content available at all)[*]
  6.3.0->6.x.x	Use regular opensource account (see above)

[*] Create function is_feature.is_lts() which will check from the 5.15 and 6.2 versions are they in LTS mode, there will be 6.5 later. Use that function to check the LTS status.