fix: remove newlines from VPA recommendations

[omerap12]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Originally reported by @adrianmoisey, this PR fixes a logging issue in the VPA updater where multi-line log entries were causing structured log output to be split and harder to read. When logging pod recommendations, newline characters were causing the output to span multiple lines:

"Pod accepted for update" pod="vertical-pod-autoscaling-7847/hamster-795f8c8794-7p52p" updatePriority=1.3449756180899484 processedRecommendations=
hamster: target: 587805k 247m; uncappedTarget: 587805k 247m;
>

The fix modifies the recommendation formatting to keep everything on a single line for better readability:

"Pod accepted for update" pod="vertical-pod-autoscaling-7847/hamster-795f8c8794-7p52p" updatePriority=1.3449756180899484 processedRecommendations="hamster: target: 587805k 247m; uncappedTarget: 587805k 247m;"

Additional tests were added to verify the logging format for single and multiple container scenarios.

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.:

NONE

[adrianmoisey]

/lgtm

[raywainman]

/lgtm

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: omerap12, raywainman

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• vertical-pod-autoscaler/OWNERS [raywainman]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment