Remove hack around broken rust update (bsc#1262022)

[dirkmueller]

It is now broken differently, so remove this workaround for now. we can
not build a new one for the other issue.

[github-actions]

Created a staging project on OBS for 7: home:pushman:BCI:Staging:SLE-15-SP7:7-3666
Changes pushed to branch 7-3666 as commit 17554215640003e42bca381e9121b1e4c24a903f
Build succeeded ✅

Build Results

Repository images in home:pushman:BCI:Staging:SLE-15-SP7:7-3666 for x86_64: current state: published
Build results:

package name	status	build log
rust-oldstable-image	⛔ excluded	live log
rust-stable-image	⛔ excluded	live log

Repository images in home:pushman:BCI:Staging:SLE-15-SP7:7-3666 for aarch64: current state: published
Build results:

package name	status	build log
rust-oldstable-image	⛔ excluded	live log
rust-stable-image	⛔ excluded	live log

Repository images in home:pushman:BCI:Staging:SLE-15-SP7:7-3666 for s390x: current state: published
Build results:

package name	status	build log
rust-oldstable-image	⛔ excluded	live log
rust-stable-image	⛔ excluded	live log

Repository images in home:pushman:BCI:Staging:SLE-15-SP7:7-3666 for ppc64le: current state: published
Build results:

package name	status	build log
rust-oldstable-image	⛔ excluded	live log
rust-stable-image	⛔ excluded	live log

Repository containerfile in home:pushman:BCI:Staging:SLE-15-SP7:7-3666 for x86_64: current state: published
Build results:

package name	status	build log
rust-oldstable-image	✅ succeeded	live log
rust-stable-image	✅ succeeded	live log

Repository containerfile in home:pushman:BCI:Staging:SLE-15-SP7:7-3666 for aarch64: current state: published
Build results:

package name	status	build log
rust-oldstable-image	✅ succeeded	live log
rust-stable-image	✅ succeeded	live log

Repository containerfile in home:pushman:BCI:Staging:SLE-15-SP7:7-3666 for s390x: current state: published
Build results:

package name	status	build log
rust-oldstable-image	✅ succeeded	live log
rust-stable-image	✅ succeeded	live log

Repository containerfile in home:pushman:BCI:Staging:SLE-15-SP7:7-3666 for ppc64le: current state: published
Build results:

package name	status	build log
rust-oldstable-image	✅ succeeded	live log
rust-stable-image	✅ succeeded	live log

Build succeeded ✅

To run BCI-tests against this PR, use the following command:

OS_VERSION=15.7 TARGET=custom BASEURL=registry.opensuse.org/home/pushman/bci/staging/sle-15-sp7/7-3666/ tox -- -n auto

The following images can be pulled from the staging project:

• registry.opensuse.org/home/pushman/bci/staging/sle-15-sp7/7-3666/containerfile/bci/rust:latest