feat: use HOSTNAME as controller name and add default value.

[tao12345666333]

Type of change:

• Bugfix
• New feature provided
• Improve performance
• Backport patches
• Documentation
• Refactor
• Chore
• CI/CD or Tests

What this PR does / why we need it:

2023-08-31T02:45:31Z	info	ingress/ingress.go:145	start ingress controller
2023-08-31T02:45:31Z	error	providers/controller.go:236	failed to create leader elector: Lock identity is empty
2023-08-31T02:45:31Z	error	providers/controller.go:156	failed to setup leader election
failed to run ingress controller: Lock identity is empty
FAIL	github.com/apache/apisix-ingress-controller/cmd/ingress	0.056s

https://github.com/apache/apisix-ingress-controller/actions/runs/6032435340/job/16367603625?pr=1936#step:4:154

Pre-submission checklist:

• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
• Have you modified the corresponding document?
• Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first

[codecov-commenter]

Codecov Report

Merging #1946 (65f0751) into master (0bbdc4f) will not change coverage.
The diff coverage is n/a.

❗ Current head 65f0751 differs from pull request most recent head 1a26453. Consider uploading reports for the commit 1a26453 to get more accurate results

@@           Coverage Diff           @@
##           master    #1946   +/-   ##
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  Coverage   36.87%   36.87%           
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  Files          93       93           
  Lines        7851     7851           
=======================================
  Hits         2895     2895           
  Misses       4568     4568           
  Partials      388      388           

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