Fix [EI-2432] EI cannot re-connect to MB after DB failure

[abeykoon]

Purpose

Fix issue https://github.com/wso2/product-ei/issues/2432

Goals

Fixing an issue regarding EI re-connect to MB after DB failure at MB.

Approach

A separate executor service is introduced to notify the connection exception listeners. We cannot use the JOB pool threads for notifying the exception listeners since it will block the frame processing which is critical for activities like connection handshakes.

User stories

EI should automatically reconnect once MB recovers from failure

Release note

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Documentation

Link(s) to product documentation that addresses the changes of this PR. If no doc impact, enter “N/A” plus brief explanation of why there’s no doc impact

Training

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Certification

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Marketing

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Automation tests

• Unit tests

  Not added

• Integration tests

  Not Added

Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines? yes
• Ran FindSecurityBugs plugin and verified report? yes
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets? yes

Samples

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Related PRs

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Migrations (if applicable)

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Test environment

JDK 8

Learning

N/A