fix: enable --skip-schema-validation on any Helm that supports it

[karthikeyangs9]

Problem

Customers running the setup script hit a hard failure during opentelemetry-operator install:

Error: values don't meet the specifications of the schema(s) in the following chart(s):
"file:///values.schema.json#" is not valid against metaschema ...
  - at '/properties/manager/properties/featureGates/examples': got string, want array
[ERROR] Helm install/upgrade failed for opentelemetry-operator.

The upstream chart's values.schema.json declares manager.featureGates.examples as a string, but the JSON Schema metaschema (draft 2019-09) requires an array. Helm 3.18.5 made this metaschema validation strict (a security hardening), so installs abort before any resource is applied.

Root cause

The script already had the right workaround — --skip-schema-validation — but gated it on helm major >= 4. The strict validation lands in 3.18.5, not v4. So developers on Helm v4 saw it work, while every customer on Helm 3.18.5–3.x got no flag and failed.

Fix

Replace version-number parsing with a capability probe:

detect_helm_schema_flag() {
    if helm upgrade --help 2>/dev/null | grep -q -- '--skip-schema-validation'; then
        HELM_SCHEMA_FLAG="--skip-schema-validation"
        ...
    fi
}

The flag is now enabled on every Helm that supports it (3.16+ and v4), and the check is immune to future version-string format changes. K8s admission controllers still validate every rendered resource, so skipping client-side schema validation is safe. $HELM_SCHEMA_FLAG already flows into all install paths (operator, collector, monitoring, kube-events).

No Helm upgrade/downgrade required — customers keep their existing Helm.

Tests

3 bats regression tests in tests/unit.bats: flag enabled when supported, the Helm 3.18.5 (major 3) customer case, and old Helm leaving it empty. Assertions are the last command in each test (bats has no implicit set -e).

Verification

Run (operator chart 0.92.1, real flags)	Result
helm template ... --skip-schema-validation	exit 0 — full manifest renders (Deployment, 4 CRDs, webhooks, RBAC)
helm template ... without the flag	reproduces the exact examples: got string, want array error
bats tests/unit.bats	22 passed, 0 failed