* Rename variables and functions to match Go convention.
For example, UsageError --> UsageErrorf.
* Remove redundant or unreachable code.
* Simplify some utility functions (no functionality changes).
* Fix hanging 'if { return } else { return }' constructs.
* Fix several incorrect printf verbs.
Automatic merge from submit-queue
Enhance message in cluster-info dump
**What this PR does / why we need it**:
This PR fixes the information message prints in the end after the cluster-info dump command.
- Added newline in the end
- Enhanced the message for dumping information to standard out
**Which issue this PR fixes** *
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
Automatic merge from submit-queue
Fixed `kubectl cluster-info dump` to support multi-container pod.
Fixed `kubectl cluster-info dump` to support multi-container pod.
**Release note**:
```
Improve `kubectl cluster-info dump` to support multi-container pod information dump.
```
Fixed#44069
Switch to allowing missing keys in jsonpath templates by default.
Add support for allowing/disallowing missing keys in go templates
(default=allow).
Add --allow-missing-template-keys flag to control this behavior
(default=true / allow missing keys).