chore: use client.OjectKeyFromObject in client.Get() and add k8serr as alias

[zdtsw]

Description

• use k8serr as alias to match other places in the code
• use OjectKeyFromObject with object already set for .Get()

local build: 'quay.io/wenzhou/opendatahub-operator:2.19.1014-1'

How Has This Been Tested?

Screenshot or short clip

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• The developer has manually tested the changes and verified that the changes work

[lburgazzoli]

Further improvements on the logic can be made on a separate PR, so this LGTM
@ykaliuta WDYT ?

[ykaliuta]

Further improvements on the logic can be made on a separate PR, so this LGTM @ykaliuta WDYT ?

agree

[openshift-ci]

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