make enterprise-server does not set `TiDBEnterpriseExtensionGitHash`

[lcwangchao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

make enterprise-server

output is:

# git submodule init && git submodule update --force
cd pkg/extension/enterprise/generate && GO111MODULE=on go generate -run genfile main.go
CGO_ENABLED=1 GO111MODULE=on go build  -tags codes -tags enterprise  -ldflags '-X "github.com/pingcap/tidb/pkg/parser/mysql.TiDBReleaseVersion=v7.5.0-alpha-116-g135d614f47" -X "github.com/pingcap/tidb/pkg/util/versioninfo.TiDBBuildTS=2023-10-16 04:52:11" -X "github.com/pingcap/tidb/pkg/util/versioninfo.TiDBGitHash=135d614f4714bec2773237692c8fd40dd9af047b" -X "github.com/pingcap/tidb/pkg/util/versioninfo.TiDBGitBranch=master" -X "github.com/pingcap/tidb/pkg/util/versioninfo.TiDBEdition=Enterprise"  ' -o bin/tidb-server cmd/tidb-server/main.go

TiDBEnterpriseExtensionGitHash should be set but not.

./bin/tidb-server -V

output:

Release Version: v7.5.0-alpha-116-g135d614f47
Edition: Enterprise
Git Commit Hash: 135d614f4714bec2773237692c8fd40dd9af047b
Git Branch: master
UTC Build Time: 2023-10-16 04:52:11
GoVersion: go1.21.0
Race Enabled: false
Check Table Before Drop: false
Store: unistore

2. What did you expect to see? (Required)

TiDBEnterpriseExtensionGitHash should be set and we should have a enterprise commit hash for ./bin/tidb-server -V

3. What did you see instead (Required)

TiDBEnterpriseExtensionGitHash not set

4. What is your TiDB version? (Required)

master

[lcwangchao]

Two reasons:

1. *: Fix portability issue in Makefile.common #43414 makes -a to -d to determine if extension/enterprise/.git exists. But ``extension/enterprise/.git` is a file, not a folder, so this will always be false.
2. *: move most of the packages to 'pkg' #47123 lost to rename extension/enterprise to pkg/extension/enterprise in the same position