Skip script when build

[DimiDr0l]

To Reproduce
Steps to reproduce the behavior:

1. When building a container, END_OF_RUN is skipped

INFO[0008] RUN --mount=type=cache,target=/var/cache/apk,sharing=locked     --mount=type=cache,target=/root/.npm,sharing=locked <<END_OF_RUN 
INFO[0008] Initializing snapshotter ...                 
INFO[0008] Taking snapshot of full filesystem...        
INFO[0008] Cmd: /bin/sh                                 
INFO[0008] Args: [-c <<END_OF_RUN]                      
INFO[0008] Running: [/bin/sh -c <<END_OF_RUN]   

Additional Information

• Dockerfile

ARG CONTAINER_VERSION="3.12.7-slim-bookworm"
FROM python:${CONTAINER_VERSION}

WORKDIR /app

COPY requirements.txt .

RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
    --mount=type=cache,target=/var/lib/apt,sharing=locked   \
<<END_OF_RUN
set -x

groupadd --system --gid 1000 app
useradd --system --gid app --uid 1000 --shell /bin/bash --create-home app
apt-get update
apt-get upgrade -y
pip install --no-cache-dir -r requirements.txt
rm requirements.txt

END_OF_RUN

USER app

• Kaniko Image gcr.io/kaniko-project/executor:v1.23.2-debug

Triage Notes for the Maintainers

Description	Yes/No
Please check if this a new feature you are proposing
Please check if the build works in docker but not in kaniko
Please check if this error is seen when you use --cache flag
Please check if your dockerfile is a multistage dockerfile

[mzihlmann]

EOF syntax is currently not yet supported by kaniko

#1713