[charts/portal] Update portal Image tags

[kk632390]

5.1 Portal Images

• Removed Solr from Readme
• Not Updated yet is the help link in create-tenant.sh with 5.1 help link https://techdocs.broadcom.com/us/en/ca-enterprise-software/layer7-api-management/api-developer-portal/5-0/install-configure-and-upgrade/post-installation-tasks/enroll-a-layer7-api-gateway.html

Benefits

Drawbacks

Applicable issues

• fixes #

Additional information

Checklist

• [X] Chart version bumped in Chart.yaml according to semver.
• [X] Variables are documented in the README.md
• [X] Title of the PR starts with chart name (e.g. [charts/gateway])
• [X] If the chart contains a values-production.yaml apart from values.yaml, ensure that you implement the changes in both files