Changes enter a validation of the template before creating a change s…

…et or updating a stack. According to AWS SDK, it will check for template syntax only (json or yml). It will throw an exception if format is incorrect. Otherwise, validation just returns a ValidateTemplateResult. (spinnaker#4602) (spinnaker#4606)

Co-authored-by: Ariadna Rouco <ariadna.rouco@adevinta.com>
(cherry picked from commit ed76ff4)

Co-authored-by: Aria <ariadna.rouco@gmail.com>
Co-authored-by: Ethan Rogers <ethanfrogers@users.noreply.github.com>

fix(aws): call correct constructor when autowiring DefaultScalingPoli…

…cyCopier (spinnaker#3528)

feat(amazon): use semantically meaningful name when copying scaling p…

…olicies (spinnaker#3526)

fix(provider/google): Paginates autoscaler aggregated list calls. (sp…

…innaker#3518) (spinnaker#3523)

fix(aws): ALB support for serving pendingOnDemandRequests (spinnaker#…

…3509)

feat(aws): Remove all ec2-classic migration code (spinnaker#3510)

fix(aws): fix ALB onDemand caching (spinnaker#3505)

refactor(boot2): Groovy compilation, removal of deprecated bad stuff

fix(aws): use asg.instances to resolve instance members instead of ca…

…che relationships (spinnaker#3503)

fix(titus): remove TitusHealthIndicator (spinnaker#3499)