tkn p/t start --showlog uses --prefix=false flag by default

[VeereshAradhya]

Versions and Operating System

• Kubernetes version:

  Output of kubectl version:

  Client Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.0", GitCommit:"5797eaecac19b9c0e4d10d3d6b559c074e3c3c88", GitTreeState:"clean", BuildDate:"2021-01-27T07:28:48Z", 
  GoVersion:"go1.15.5", Compiler:"gc", Platform:"linux/amd64"}
  Server Version: version.Info{Major:"1", Minor:"21+", GitVersion:"v1.21.0-rc.0+120883f", GitCommit:"120883fe7ff642c7de79ec1e533e4c63cf099eb0", GitTreeState:"clean", BuildDate:"2021-06-12T07:15:42Z", GoVersion:"go1.16.4", Compiler:"gc", Platform:"linux/amd64"}
  
  

• Tekton Pipeline version:

  Output of tkn version or kubectl get pods -n tekton-pipelines -l app=tekton-pipelines-controller -o=jsonpath='{.items[0].metadata.labels.version}'

  $ tkn version
  Client version: 0.19.0
  Pipeline version: v0.22.0
  Triggers version: v0.12.1
  
  

• Operating System:

  ALL
  

Expected Behavior

tkn p/t start --showlog should not use --prefix=false flag by default

Actual Behavior

tkn p/t start --showlog uses --prefix=false flag by default

Steps to Reproduce the Problem

1. Create a task/pipeline
2. Start task/pipeline using the command tkn p/t start <pipeline-name>/<task-name> --showlog

Additional Info

Command execution log

$ tkn p start cli-test-pipeline -L --showlog
PipelineRun started: cli-test-pipeline-run-ks5xg
Waiting for logs to be available...
+ CHECKOUT_DIR=/workspace/output/
+ [[ true == \t\r\u\e ]]
+ cleandir
+ [[ -d /workspace/output/ ]]
+ rm -rf /workspace/output//lost+found
+ rm -rf '/workspace/output//.[!.]*'
+ rm -rf '/workspace/output//..?*'
+ test -z ''
+ test -z ''
+ test -z ''