fix: shutdown-manager not respecting security context of container spec

[Dean-Coakley]

What type of PR is this?
Fixes setting custom security context in container spec

Note: I have not taken any steps to test my changes outside of my unit test. If this is required please provide some guidance on the best way to do so

Which issue(s) this PR fixes:

Fixes #4881

Release Notes: Yes

[zhaohuabing]

@Dean-Coakley
Please fix lint:

internal/infrastructure/kubernetes/proxy/resource_test.go:11: File is not `gci`-ed with --skip-generated -s standard -s default -s prefix(github.com/envoyproxy/gateway) (gci)
	egv1a1 "github.com/envoyproxy/gateway/api/v1alpha1"
	"github.com/envoyproxy/gateway/internal/infrastructure/kubernetes/resource"

internal/infrastructure/kubernetes/proxy/resource_test.go:16: File is not `gci`-ed with --skip-generated -s standard -s default -s 

And run make gen-check and submit the changes to fix then gen check.

[Dean-Coakley]

@zhaohuabing Are there some prerequisites, or do you have suggestions on how to resolve?:

$ golangci-lint version
golangci-lint has version 1.59.1 built with go1.22.3 from 1a55854a on 2024-06-09T18:08:33Z
$ go version
go version go1.23.3 linux/amd64

$ make gen-check
make[1]: Entering directory '/home/dean/go/src/github.com/dean-coakley/envoy-gateway'
===========> Running go.mod.tidy ... 
go mod tidy -compat=1.23
go: github.com/envoyproxy/gateway/internal/troubleshoot imports
	github.com/replicatedhq/troubleshoot/pkg/collect imports
	github.com/replicatedhq/troubleshoot/pkg/debug imports
	github.com/spf13/viper imports
	github.com/spf13/viper/internal/encoding/toml imports
	github.com/pelletier/go-toml/v2: mkdir /home/dean/go/pkg/mod/github.com/pelletier/go-toml: permission denied
make[1]: *** [tools/make/golang.mk:81: go.mod.tidy] Error 1
make[1]: Leaving directory '/home/dean/go/src/github.com/dean-coakley/envoy-gateway'
make: *** [Makefile:18: _run] Error 2

$ sudo make gen-check    
make[1]: Entering directory '/home/dean/go/src/github.com/dean-coakley/envoy-gateway'
/bin/bash: line 1: go: command not found
/bin/bash: line 1: go: command not found
/bin/bash: line 1: go: command not found
===========> Running go.mod.tidy ... 
go mod tidy -compat=1.23
/bin/bash: line 1: go: command not found
make[1]: *** [tools/make/golang.mk:81: go.mod.tidy] Error 127
make[1]: Leaving directory '/home/dean/go/src/github.com/dean-coakley/envoy-gateway'
make: *** [Makefile:18: _run] Error 2

[zhaohuabing]

github.com/pelletier/go-toml/v2: mkdir /home/dean/go/pkg/mod/github.com/pelletier/go-toml: permission denied

@Dean-Coakley

Can you try
sudo rm -rf /home/dean/go/pkg/mod/
and then
make gen-check