Upgrade snappi version to 0.7.44 (sonic-net#11335)

Why I did it
Keysight provide a new version with some snappi API source code related fix: snappi[ixnetwork,convergence]==0.7.44

How I did it
Upgrade snappi version to 0.7.44

How to verify it
Whether it's installed in sonic-mgmt docker container

Author: yejianquan

dockers/docker-sonic-mgmt/Dockerfile.j2

@@ -43,7 +43,7 @@ RUN pip install cffi==1.10.0 \
                 ipython==5.4.1 \
                 ixnetwork-restpy==1.0.64 \
                 ixnetwork-open-traffic-generator==0.0.79 \
-                snappi[ixnetwork,convergence]==0.5.11 \
+                snappi[ixnetwork,convergence]==0.7.44 \
                 jinja2==2.7.2 \
                 jsonpatch \
                 lxml \
@@ -207,7 +207,7 @@ RUN python3 -m pip install setuptools-rust \
                             ipython==5.4.1 \
                             ixnetwork-restpy==1.0.64 \
                             ixnetwork-open-traffic-generator==0.0.79 \
-                            snappi[ixnetwork,convergence]==0.5.11 \
+                            snappi[ixnetwork,convergence]==0.7.44 \
                             jinja2==2.7.2 \
                             jsonpatch \
                             lxml \