Refactor Codegen Dockerfile

[Okabe-Junya]

What this PR does:

• Change codegen Dockerfile base image from golang:1.25.2 to debian:bookworm-slim
• Use multi-stage build to compile Go plugins in builder stage and copy only binaries to final image
• Update Go version from 1.25.2 to 1.25.5
• Remove wget and ca-certificates after use

Why we need it:

• Reduce attack surface by removing Go runtime from final image
• Address curl-related CVEs (CVE-2025-9086, CVE-2025-10148, CVE-2025-11563) flagged in PR [Snyk] Security upgrade golang from 1.25.2 to 1.26rc1 #6379
• Avoid using RC (release candidate) version of Go proposed by Snyk
• Minimize image size and unnecessary dependencies

Which issue(s) this PR fixes:

cf. #6379 (review)

Does this PR introduce a user-facing change?:

• How are users affected by this change:
• Is this breaking change:
• How to migrate (if breaking change):

[khanhtc1202]

Great improvement, thanks 👍

[khanhtc1202]

Note: Try re-gen the new container image on CI after this been merged

[khanhtc1202]

@Okabe-Junya Tested on my local and look like the built container image missed some protoc lib.

google/protobuf/descriptor.proto: File not found.
google/protobuf/duration.proto: File not found.
google/protobuf/timestamp.proto: File not found.
validate/validate.proto:7:1: Import "google/protobuf/descriptor.proto" was not found or had errors.
validate/validate.proto:8:1: Import "google/protobuf/duration.proto" was not found or had errors.
validate/validate.proto:9:1: Import "google/protobuf/timestamp.proto" was not found or had errors.
validate/validate.proto:798:14: "google.protobuf.Duration" is not defined.
validate/validate.proto:802:14: "google.protobuf.Duration" is not defined.
validate/validate.proto:806:14: "google.protobuf.Duration" is not defined.
validate/validate.proto:810:14: "google.protobuf.Duration" is not defined.
validate/validate.proto:814:14: "google.protobuf.Duration" is not defined.
validate/validate.proto:818:14: "google.protobuf.Duration" is not defined.
validate/validate.proto:822:14: "google.protobuf.Duration" is not defined.
validate/validate.proto:832:14: "google.protobuf.Timestamp" is not defined.
validate/validate.proto:836:14: "google.protobuf.Timestamp" is not defined.
validate/validate.proto:840:14: "google.protobuf.Timestamp" is not defined.
validate/validate.proto:844:14: "google.protobuf.Timestamp" is not defined.
validate/validate.proto:848:14: "google.protobuf.Timestamp" is not defined.
validate/validate.proto:861:14: "google.protobuf.Duration" is not defined.
validate/validate.proto:12:8: "google.protobuf.MessageOptions" is not defined.
validate/validate.proto: "google.protobuf.MessageOptions" is not defined.
validate/validate.proto:21:8: "google.protobuf.OneofOptions" is not defined.
validate/validate.proto:28:8: "google.protobuf.FieldOptions" is not defined.
pkg/model/analysis_result.proto:20:1: Import "validate/validate.proto" was not found or had errors.
make: *** [gen/code] Error 1

After I fixed the missing lib issue, it turned out we need to use the go command for mockgen 😓

- pkg/redis/redistest/redis.mock.go
generating mock...
2026/01/06 08:13:49 Loading input failed: load package: load packages: err: go command required, not found: exec: "go": executable file not found in $PATH: stderr: 
make: *** [gen/code] Error 1

So basically we need to use a Go container image for this codegen process (or have to find a way to separate protoc and mock into 2 different codegen images).

I will revert the commit till we find a way for better codegen image (as you pointed out)