I think the error message is confusing. Access to the tridion_cm database is failing, and because of that, the login for your User (WORKGROUP\EC2AMAZ-TUJ3HK0$) fails. This does not mean that the database connection makes use of your user's credentials, at least I hope not.
You should check the database credentials configured for the content manager. This ...
Failure to prepare for deployment often indicates a false Content Deployer configuration or problems with customizations.
If your publishing fails in the'Preparing for deployment' phase, try the following:
Is your Content Deployer configuration (deployer-conf.xml) correct?
Are you using a custom Module and/or Processor in your Content Deployer? The code for ...
Answer to your questions:
Q: Is the reference document mentioned is good enough for this upgrade?
A: Yes. High-level steps
Q: I am using SDL Web 8.5 and trying DXA 2.2.9 which uses GraphQL as providers?
A: There is no PCA Graphql feature in 8.5, It's available only from sites 9.0+ versions, you need to update your unity.config to use CIL Defaultproviders ...