fix: set prebuilds lifecycle parameters on creation and claim (#19252)

## Description

This PR ensures that prebuilt workspaces are properly excluded from the
lifecycle executor and treated as a separate class of workspaces, fully
managed by the prebuild reconciliation loop.

It introduces two lifecycle guarantees:
* When a prebuilt workspace is created (i.e., when the workspace build
completes), all lifecycle-related fields are unset, ensuring the
workspace does not participate in TTL, autostop, autostart, dormancy, or
auto-deletion logic.
* When a prebuilt workspace is claimed, it transitions into a regular
user workspace. At this point, all lifecycle fields are correctly
populated according to template-level configurations, allowing the
workspace to be managed by the lifecycle executor as expected.

## Changes

* Prebuilt workspaces now have all lifecycle-relevant fields unset
during creation
* When a prebuild is claimed:
* Lifecycle fields are set based on template and workspace level
configurations. This ensures a clean transition into the standard
workspace lifecycle flow.
* Updated lifecycle-related SQL update queries to explicitly exclude
prebuilt workspaces.

## Relates 

Related issue: https://github.com/coder/coder/issues/18898

To reduce the scope of this PR and make the review process more
manageable, the original implementation has been split into the
following focused PRs:
* https://github.com/coder/coder/pull/19259
* https://github.com/coder/coder/pull/19263
* https://github.com/coder/coder/pull/19264
* https://github.com/coder/coder/pull/19265

These PRs should be considered in conjunction with this one to
understand the complete set of lifecycle separation changes for prebuilt
workspaces.

enterprise/coderd/schedule/template.go

@@ -205,7 +205,6 @@ func (s *EnterpriseTemplateScheduleStore) Set(ctx context.Context, db database.S
 			if opts.DefaultTTL != 0 {
 				ttl = sql.NullInt64{Valid: true, Int64: int64(opts.DefaultTTL)}
 			}
-
 			if err = tx.UpdateWorkspacesTTLByTemplateID(ctx, database.UpdateWorkspacesTTLByTemplateIDParams{
 				TemplateID: template.ID,
 				Ttl:        ttl,