fixing the issue with RDS storage #

[qburst-praven]

What type of PR is this?
Bug

What this PR does / why we need it:
At present if you run the docker compose it breaks for RDS with the error

"Could not get rds storage price" error="Price list response should be equal only to 1 product" storage_filters="{\n Filters: [\n {\n Field: "volumeType",\n Type: "TERM_MATCH",\n Value: "General Purpose"\n },\n {\n Field: "productFamily",\n Type: "TERM_MATCH",\n Value: "Database Storage"\n },\n {\n Field: "termType",\n Type: "TERM_MATCH",\n Value: "OnDemand"\n },\n {\n Field: "deploymentOption",\n Type: "TERM_MATCH",\n Value: "Single-AZ"\n }\n ],\n ServiceCode: "AmazonRDS"\n}"

This is because the current filter does not add databaseEngine. This PR adds the same and fixes the issue.