Set the maximum open connections limit in PG and MySQL target configs

[Praveenrajmani]

Description

As the bulk/recursive delete will require multiple connections to open at once,
The default open connections limit will be reached which results in the following error

FATAL: sorry, too many clients already

By setting the open connections to a reasonable value - 2, We ensure that the max open connections
will not be exhausted and lie under bounds.

The queries are simple inserts/updates/deletes which is operational and sufficient with the
maximum open connection limit being 2.

Motivation and Context

Fixes #10553

How to test this PR?

The steps are provided in #10554

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• Fixes a regression (If yes, please add commit-id or PR # here)
• Documentation needed
• Unit tests needed

[Praveenrajmani]

Can we add MaxOpenConns as a config setting @harshavardhana ? So that, the user can set their own limits.

[harshavardhana]

Can we add MaxOpenConns as a config setting @harshavardhana ? So that, the user can set their own limits.

Yes we can @Praveenrajmani

[Praveenrajmani]

The PR is ready for review. PTAL @harshavardhana

[kannappanr]

LGTM

[minio-trusted]

Mint Automation

Test	Result
mint-large-bucket.sh	✔️
mint-fs.sh	✔️
mint-gateway-s3.sh	✔️
mint-erasure.sh	✔️
mint-dist-erasure.sh	✔️
mint-zoned.sh	✔️
mint-gateway-nas.sh	✔️
mint-gateway-azure.sh	❌ more...

10558-57b9edc/mint-gateway-azure.sh.log:

Running with
SERVER_ENDPOINT:      minio-dev6.minio.io:30164
ACCESS_KEY:           minioazure
SECRET_KEY:           ***REDACTED***
ENABLE_HTTPS:         0
SERVER_REGION:        us-east-1
MINT_DATA_DIR:        /mint/data
MINT_MODE:            full
ENABLE_VIRTUAL_STYLE: 0

To get logs, run 'docker cp 8c40f82e140f:/mint/log /tmp/mint-logs'

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(8/15) Running minio-dotnet tests ... done in 1 minutes and 36 seconds
(9/15) Running minio-go tests ... FAILED in 1 minutes and 49 seconds
{
  "args": {
    "bucketName": "minio-go-test-nknho10o5soblfwg",
    "objectName": "test-object",
    "opts": "",
    "size": -1
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  "duration": 1032,
  "function": "PutObject(bucketName, objectName, reader,size,opts)",
  "message": "Unexpected size",
  "name": "minio-go: testPutObjectStreaming",
  "status": "FAIL"
}
(9/15) Running minio-java tests ... done in 10 minutes and 38 seconds
(10/15) Running minio-js tests ... FAILED in 46 seconds
{
  "name": "minio-js",
  "function": "\"after all\" hook in \"functional tests\"",
  "duration": 81,
  "status": "FAIL",
  "error": "S3Error: The bucket you tried to delete is not empty at Object.parseError (node_modules/minio/dist/main/xml-parsers.js:86:11) at /mint/run/core/minio-js/node_modules/minio/dist/main/transformers.js:156:22 at DestroyableTransform._flush (node_modules/minio/dist/main/transformers.js:80:10) at DestroyableTransform.prefinish (node_modules/readable-stream/lib/_stream_transform.js:129:10) at prefinish (node_modules/readable-stream/lib/_stream_writable.js:611:14) at finishMaybe (node_modules/readable-stream/lib/_stream_writable.js:620:5) at endWritable (node_modules/readable-stream/lib/_stream_writable.js:643:3) at DestroyableTransform.Writable.end (node_modules/readable-stream/lib/_stream_writable.js:571:22) at IncomingMessage.onend (_stream_readable.js:682:10) at endReadableNT (_stream_readable.js:1252:12) at processTicksAndRejections (internal/process/task_queues.js:80:21)"
}
(10/15) Running minio-py tests ... done in 19 minutes and 14 seconds
(11/15) Running s3cmd tests ... done in 2 minutes and 25 seconds
(12/15) Running s3select tests ... done in 41 seconds
(13/15) Running security tests ... done in 0 seconds

Executed 13 out of 15 tests successfully.

Deleting image on docker hub
Deleting image locally
Error: No such image: minio/minio:10558-57b9edc