Remove Docker build warnings

[LoginovIlia]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

When building an image, for example when you run make test-in-docker.
Docker prints warnings:

make test-in-docker
rm -f cluster-autoscaler-amd64
docker build --network=default -t autoscaling-builder ../builder
[+] Building 0.6s (9/9) FINISHED                                                                                                                                                 docker:desktop-linux
 => [internal] load build definition from Dockerfile                                                                                                                                             0.0s
 => => transferring dockerfile: 891B                                                                                                                                                             0.0s
 => [internal] load metadata for docker.io/library/golang:1.24.0                                                                                                                                 0.5s
 => [internal] load .dockerignore                                                                                                                                                                0.0s
 => => transferring context: 2B                                                                                                                                                                  0.0s
 => [1/5] FROM docker.io/library/golang:1.24.0@sha256:3f7444391c51a11a039bf0359ee81cc64e663c17d787ad0e637a4de1a3f62a71                                                                           0.0s
 => CACHED [2/5] RUN apt-get update && apt-get --yes install libseccomp-dev                                                                                                                      0.0s
 => CACHED [3/5] RUN go version                                                                                                                                                                  0.0s
 => CACHED [4/5] RUN go install github.com/tools/godep@latest                                                                                                                                    0.0s
 => CACHED [5/5] RUN godep version                                                                                                                                                               0.0s
 => exporting to image                                                                                                                                                                           0.0s
 => => exporting layers                                                                                                                                                                          0.0s
 => => writing image sha256:10eadd62e605aabb6ccfa63d0035bcf8f3078553cec842e8e3c15612b3fa552e                                                                                                     0.0s
 => => naming to docker.io/library/autoscaling-builder                                                                                                                                           0.0s

 3 warnings found (use docker --debug to expand):
 - LegacyKeyValueFormat: "ENV key=value" should be used instead of legacy "ENV key value" format (line 17)
 - LegacyKeyValueFormat: "ENV key=value" should be used instead of legacy "ENV key value" format (line 18)
 - LegacyKeyValueFormat: "ENV key=value" should be used instead of legacy "ENV key value" format (line 19)

P.S. Similar warnings were removed earlier in PR: #7457

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

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This pull-request has been approved by: LoginovIlia
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[k8s-ci-robot]

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