iwyu.yml: use fedora:rawhide to get the very latest packages / dropped some workarounds [skip ci]

[firewave]

No description provided.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[firewave]

Still waiting for include-what-you-use 0.26 to actually hit rawhide (it should already according to Fedoras index) to see that it works without the workarounds.

[firewave]

Still waiting for include-what-you-use 0.26 to actually hit rawhide (it should already according to Fedoras index) to see that it works without the workarounds.

Now fails with

Failed to resolve the transaction:
Problem: conflicting requests
  - nothing provides libiwyu.so.22.1()(64bit) needed by iwyu-0.26-1.fc45.x86_64 from rawhide