ipam: Reduce git actions noise (#1875)

When kubevirt-bot creates PRs, it will trigger the IPAM lane twice, because both
`push` and `pull_request` events occur (the bot creates a branch on main,
hence push event happens).
The IPAM lane also runs after a PR is merged, because it triggers `push`.
In order to reduce this noise, lets remove the `push` event.
The `pull_request` is enough as long as PRs are used
(and not direct pushes which aren't encouraged anyhow).

Signed-off-by: Or Shoval <[email protected]>

.github/workflows/kubevirt-ipam-controller.yaml

@@ -1,5 +1,5 @@
 name: Kubevirt IPAM controller Tests
-on: [push, pull_request]
+on: [pull_request]
 jobs:
   e2e:
     runs-on: ubuntu-latest