Removed standalone server and added dev index

[awanlin]

Hey, I just made a Pull Request!

Removed standalone server and added dev index for backend plugins. This is work towards #413

✔️ Checklist

• A changeset describing the change and affected packages. (more info)
• Added or updated documentation
• Tests for new functionality and regression tests for bug fixes
• Screenshots attached (for UI changes)
• All your commits have a Signed-off-by line in the message. (more info)

[backstage-goalie]

Missing Changesets

The following package(s) are changed by this PR but do not have a changeset:

• @backstage-community/plugin-airbrake-backend
• @backstage-community/plugin-azure-sites-backend
• @backstage-community/plugin-azure-storage-explorer-backend
• @backstage-community/plugin-bazaar-backend
• @backstage-community/plugin-entity-feedback-backend
• @backstage-community/plugin-explore-backend
• @backstage-community/plugin-feedback-backend
• @backstage-community/plugin-jenkins-backend
• @backstage-community/plugin-nomad-backend
• @backstage-community/plugin-periskop-backend
• @backstage-community/plugin-playlist-backend
• @backstage-community/plugin-report-portal-backend
• @backstage-community/plugin-rollbar-backend
• @backstage-community/plugin-sonarqube-backend
• @backstage-community/plugin-vault-backend

See CONTRIBUTING.md for more information about how to add changesets.

Changed Packages

Package Name	Package Path	Changeset Bump	Current Version
@backstage-community/plugin-airbrake-backend	workspaces/airbrake/plugins/airbrake-backend	none	v0.3.18
@backstage-community/plugin-azure-sites-backend	workspaces/azure-sites/plugins/azure-sites-backend	none	v0.3.8
@backstage-community/plugin-azure-storage-explorer-backend	workspaces/azure-storage-explorer/plugins/azure-storage-backend	none	v0.0.4
@backstage-community/plugin-bazaar-backend	workspaces/bazaar/plugins/bazaar-backend	none	v0.3.17
@backstage-community/plugin-entity-feedback-backend	workspaces/entity-feedback/plugins/entity-feedback-backend	none	v0.2.21
@backstage-community/plugin-explore-backend	workspaces/explore/plugins/explore-backend	none	v0.1.5
@backstage-community/plugin-feedback-backend	workspaces/feedback/plugins/feedback-backend	none	v1.7.3
@backstage-community/plugin-jenkins-backend	workspaces/jenkins/plugins/jenkins-backend	none	v0.5.0
@backstage-community/plugin-nomad-backend	workspaces/nomad/plugins/nomad-backend	none	v0.1.23
@backstage-community/plugin-periskop-backend	workspaces/periskop/plugins/periskop-backend	none	v0.2.19
@backstage-community/plugin-playlist-backend	workspaces/playlist/plugins/playlist-backend	none	v0.3.25
@backstage-community/plugin-report-portal-backend	workspaces/report-portal/plugins/report-portal-backend	none	v1.0.3
@backstage-community/plugin-rollbar-backend	workspaces/rollbar/plugins/rollbar-backend	none	v0.1.66
@backstage-community/plugin-sonarqube-backend	workspaces/sonarqube/plugins/sonarqube-backend	none	v0.2.23
@backstage-community/plugin-vault-backend	workspaces/vault/plugins/vault-backend	none	v0.4.18