Remove constraint caching from image build (apache#38020)

Constraint caching added recently to the image caused some
unexpected side effects when conflicting constraints were added - as
old constraints cached in the image were not replaced even if main has
been updated. This PR removes caching from the image - so that building
the image will always use constraints from main.

Dockerfile

@@ -552,10 +552,6 @@ function common::get_airflow_version_specification() {
 }
 
 function common::get_constraints_location() {
-    if [[ -f "${HOME}/constraints.txt" ]]; then
-        # constraints are already downloaded, do not calculate/override again
-        return
-    fi
     # auto-detect Airflow-constraint reference and location
     if [[ -z "${AIRFLOW_CONSTRAINTS_REFERENCE=}" ]]; then
         if  [[ ${AIRFLOW_VERSION} =~ v?2.* && ! ${AIRFLOW_VERSION} =~ .*dev.* ]]; then

Dockerfile.ci

@@ -499,10 +499,6 @@ function common::get_airflow_version_specification() {
 }
 
 function common::get_constraints_location() {
-    if [[ -f "${HOME}/constraints.txt" ]]; then
-        # constraints are already downloaded, do not calculate/override again
-        return
-    fi
     # auto-detect Airflow-constraint reference and location
     if [[ -z "${AIRFLOW_CONSTRAINTS_REFERENCE=}" ]]; then
         if  [[ ${AIRFLOW_VERSION} =~ v?2.* && ! ${AIRFLOW_VERSION} =~ .*dev.* ]]; then

scripts/docker/common.sh

@@ -77,10 +77,6 @@ function common::get_airflow_version_specification() {
 }
 
 function common::get_constraints_location() {
-    if [[ -f "${HOME}/constraints.txt" ]]; then
-        # constraints are already downloaded, do not calculate/override again
-        return
-    fi
     # auto-detect Airflow-constraint reference and location
     if [[ -z "${AIRFLOW_CONSTRAINTS_REFERENCE=}" ]]; then
         if  [[ ${AIRFLOW_VERSION} =~ v?2.* && ! ${AIRFLOW_VERSION} =~ .*dev.* ]]; then