[SPARK-28906][BUILD] Fix incorrect information in bin/spark-submit --…

…version

### What changes were proposed in this pull request?
This PR allows `bin/spark-submit --version` to show the correct information while the previous versions, which were created by `dev/create-release/do-release-docker.sh`, show incorrect information.

There are two root causes to show incorrect information:

1. Did not pass `USER` environment variable to the docker container
1. Did not keep `.git` directory in the work directory

### Why are the changes needed?
The information is missing while the previous versions show the correct information.

### Does this PR introduce any user-facing change?
Yes, the following is the console output in branch-2.3

```
$ bin/spark-submit --version
Welcome to
      ____              __
     / __/__  ___ _____/ /__
    _\ \/ _ \/ _ `/ __/  '_/
   /___/ .__/\_,_/_/ /_/\_\   version 2.3.4
      /_/

Using Scala version 2.11.8, OpenJDK 64-Bit Server VM, 1.8.0_212
Branch HEAD
Compiled by user ishizaki on 2019-09-02T02:18:10Z
Revision 8c6f815
Url https://gitbox.apache.org/repos/asf/spark.git
Type --help for more information.
```

Without this PR, the console output is as follows
```
$ spark-submit --version
Welcome to
      ____              __
     / __/__  ___ _____/ /__
    _\ \/ _ \/ _ `/ __/  '_/
   /___/ .__/\_,_/_/ /_/\_\   version 2.3.4
      /_/

Using Scala version 2.11.8, OpenJDK 64-Bit Server VM, 1.8.0_212
Branch
Compiled by user on 2019-08-26T08:29:39Z
Revision
Url
Type --help for more information.
```

### How was this patch tested?
After building the package, I manually executed `bin/spark-submit --version`

Closes #25655 from kiszk/SPARK-28906.

Authored-by: Kazuaki Ishizaki <ishizaki@jp.ibm.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>

dev/create-release/do-release-docker.sh

@@ -127,6 +127,7 @@ GPG_KEY=$GPG_KEY
 ASF_PASSWORD=$ASF_PASSWORD
 GPG_PASSPHRASE=$GPG_PASSPHRASE
 RELEASE_STEP=$RELEASE_STEP
+USER=$USER
 EOF
 
 JAVA_VOL=

dev/create-release/release-build.sh

@@ -164,7 +164,6 @@ DEST_DIR_NAME="$SPARK_PACKAGE_VERSION"
 
 git clean -d -f -x
 rm .gitignore
-rm -rf .git
 cd ..
 
 if [[ "$1" == "package" ]]; then
@@ -179,7 +178,7 @@ if [[ "$1" == "package" ]]; then
     rm -r spark-$SPARK_VERSION/licenses-binary
   fi
 
-  tar cvzf spark-$SPARK_VERSION.tgz spark-$SPARK_VERSION
+  tar cvzf spark-$SPARK_VERSION.tgz --exclude spark-$SPARK_VERSION/.git spark-$SPARK_VERSION
   echo $GPG_PASSPHRASE | $GPG --passphrase-fd 0 --armour --output spark-$SPARK_VERSION.tgz.asc \
     --detach-sig spark-$SPARK_VERSION.tgz
   echo $GPG_PASSPHRASE | $GPG --passphrase-fd 0 --print-md \