Update dependency @pulumi/aws to v7.43.0 and fix nodegroup input types - #2371

TL;DR

@pulumi/aws v7.30.0 moved undefined inside the Input<> wrapper for optional inputs
SDK-wide. nodegroup.ts doesn't compile against that, which is why the bump in #2209 fails
build_provider. This PR does the bump and the type fix together so CI stays green.

Proposed changes

Bumps @pulumi/aws from 7.25.0 to 7.43.0 (same bump as #2209) and fixes the TypeScript
compile errors that bump surfaces.

Why the bump alone fails

@pulumi/aws v7.30.0 changed optional inputs SDK-wide, moving undefined inside the
Input<> wrapper:

-    amiType?:       pulumi.Input<string>;
+    amiType?:       pulumi.Input<string | undefined>;
-    instanceTypes?: pulumi.Input<pulumi.Input<string>[]>;
+    instanceTypes?: pulumi.Input<pulumi.Input<string>[] | undefined>;
-    taints?:        pulumi.Input<pulumi.Input<inputs.eks.NodeGroupTaint>[]>;
+    taints?:        pulumi.Input<pulumi.Input<inputs.eks.NodeGroupTaint>[] | undefined>;
-    version?:       pulumi.Input<string>;
+    version?:       pulumi.Input<string | undefined>;

This is codegen-wide, not EKS-specific — ec2/instance, ecs/service and rds/instance
pick up the same shape in v7.30.0.

Input<T> | undefined is assignable once null-checked; Input<T | undefined> is not, because
the undefined survives into the Promise/Output branch. Since ManagedNodeGroupOptions
derives from aws.eks.NodeGroupArgs, tsc fails with 7 errors in nodes/nodegroup.ts
(lines 2002, 2079, 2159, 2274, 2360, 2372, 2387) — which is what fails build_provider on
#2209 today, in turn skipping the test job.

The fix

Widen the affected signatures in nodes/instances.ts and nodes/nodegroup.ts to accept the
new shape and guard the resolved values, rather than casting the undefined away.

One behaviour change beyond types, in getRecommendedAMI: version now resolves with
version ?? clusterVersion. Previously an args.version that was truthy as an Output but
resolved to undefined was passed straight into ssmParameterName, producing a malformed
SSM parameter path.

These changes are backwards-compatible — the source still compiles against 7.25.0.

Verification

• tsc — clean against both 7.25.0 and 7.43.0
• yarn test — 417 tests / 10 suites / 18 snapshots pass
• yarn check-duplicate-deps — clean

Related issues

• Supersedes Update dependency @pulumi/aws to v7.54.0 #2209 — same bump, plus the type fix that bump needs to compile.
• Related to Support EKS advanced Kubernetes control plane configuration #2367 — the advanced control plane config types only exist in @pulumi/aws
  7.42.0+, so this bump is a prerequisite for that. Split out of Support advanced Kubernetes control plane configuration #2368 to keep the dependency
  change reviewable on its own.