Adding busybox image override

[r65535]

Purpose

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I am trying to run this helm chart using a private image registry, with custom image names.

Goals

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This PR should allow users to override the initContainer image and tag, similar to the WSO2 images

Approach

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Added 2 new value variables

User stories

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Release note

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Two new helm values added to allow users to override the initContainer image and tag

Documentation

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Added values to readme

Training

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Certification

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Marketing

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Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines? yes/no
• Ran FindSecurityBugs plugin and verified report? yes/no
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets? yes/no

Samples

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Related PRs

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Migrations (if applicable)

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Test environment

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Learning

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